Chapter 2, Review For Final
The outer join syntax does not apply easily to a join condition of more than ________ tables. A) two B) three C) four D) any number of
A
The total quiz points for a student for an entire semester is a(n) ________ attribute. A) derived B) mixed C) stored D) addressed
A
Attribute
A property or characteristic of an entity or relationship type that is of interest to the organization
Join
A relational operation that causes two or more tables with a common domain to be combined into a single table or view (The common columns in joined tables are usually the primary key in the dominant table and the foreign key of the dependent table)
Unary Relationship
A relationship between instances of a single entity type
Binary Relationship
A relationship between the instances of two entity types
Cardinality Constraint
A rule that specifies the number of instances of one entity that can (or must) be associated with each instance of another entity.
User-defined constraints
Added by the database designers
Mapping entities with unique composite attributes into relations
An entity whose only unique attribute is a composite attribute is mapped as a relation with a composite primary key
Natural join
An equi-join in which one of the duplicate columns is eliminated in the result table
Composite Identifier
An identifier that consists of a composite attribute
Mapping associative entities
Associative entities are mapped into relational database constructs in the identical way as M:N relationships
What result will the following SQL statement produce? Select Avg(standard_price) as average from Product_V; A) The average of all products in Product_V B) The average Standard_Price of all products in Product_V C) The average price of all products D) None of the above
B
All of the following are new data types added in SQL:200n Except: BIGINT. BIT. MULTISET. XML.
BIT.
Indexes are created in most RDBMSs to: A) provide a quicker way to store data. B) decrease the amount of disk space utilized. C) provide rapid random and sequential access to base-table data. D) increase the cost of implementation
C
RANK and DENSE-RANK are examples of: A) ceilings. B) door functions. C) window functions. D) moving functions.
C
A business rule: A) defines or constrains some aspect of the business. B) asserts business structure. C) controls or influences the behavior of the business. D) all of the above.
D
A good data definition will all of the characteristics of a data object EXCEPT: A) subtleties. B) examples. C) who determines the value of the data. D) who can delete the data.
D
A join in which the joining condition is based on equality between values in the common columns is called a(n): A) equi-join. B) unilateral join. C) natural join. D) both A and C.
D
A named set of SQL statements that are considered when a data modification occurs are called: A)stored procedures B)treatments C)trapdoors D)triggers
D
Mapping derived attributes
Derived attributes are not mapped as a part of the relational schema, They are implemented as a part of the database front-end application
Discuss the properties of relations.
Each relation (or table) has a unique name. An entry at the intersection of each row and column is atomic and each row is unique. Each attribute (or column) within a table has a unique name. The sequence of rows and columns is insignificant.
Mapping multiple relationships between the same entities
Each relationship is mapped
EXISTS takes a value of false if the sub query returns an intermediate result set
False
EXISTS takes a value of false if the subquery returns an intermediate result set.
False
IF-THEN-ELSE logical processing cannot be accomplished within an SQL statement.
False
Implementation of a standard can never stifle creativity and innovation.
False
SQL has been implemented only in the mainframe and midrange environments.
False
SQL originated from a project called System-S.
False
Specifying the attribute names in the SELECT statement will make it easier to find errors in queries and also correct for problems that may occur in the base system.
False
Subqueries can only be used in the WHERE clause.
False
The CREATE SCHEMA DDL command is used to create a table.
False
The DELETE TABLE DDL command is used to remove a table from the database.
False
The DROP command deletes rows from a table individually or in groups.
False
The HAVING clause and the WHERE clause perform the same operation.
False
The ORDER BY clause is the first statement processed in an SQL command.
False
The following command would work fine: insert into budget values 121,222,111;
False
The following query totals sales in state= 'MA' for each salesperson. Select salesperson_id, sum(sales) from salesperson group by salesperson_id having state = 'MA';
False
The following query will execute without errors. select customer.customer_name, salesman.sales_quota from customer where customer.salesman_id = (select salesman_id where lname = 'SMITH');
False
The natural join is very rarely used.
False
There is a special operation in SQL to join a table to itself.
False
Transaction integrity commands are not used to identify whole units of database changes that must be completed in full for the database to retain integrity.
False
Triggers can be used to ensure referential integrity, enforce business rules, create audit trails, replicate tables, but cannot call other triggers.
False
User-defined functions can improve system performance because they will be processed as sets rather than individually, thus reducing system overhead.
False
Using an outer join produces this information: rows that do not have matching values in common columns are not included in the result table.
False
When a subquery is used in the FROM clause, it is called a denied table.
False
When creating a table, it is not important to consider foreign key—primary key mates.
False
Referential integrity constraint lines
In a relational schema lines pointing from the foreign key to the corresponding primary key are referred to as referential integrity constraint lines
referential integrity constraint lines
In a relational schema lines pointing from the foreign key to the corresponding primary key are referred to as this.
Referential integrity constraint
In each row of a relation containing a foreign key, the value of the foreign key EITHER matches one of the values in the primary key column of the referred relation OR the value of the foreign key is null (empty).
Mapping 1:1 unary relationships
Mapped in the same way as 1:M unary relationships
Mapping entities with candidate keys (multiple unique attributes) into relations
One of the candidate keys is chosen by database designer the as a primary key during the mapping process, Other candidate keys are mapped as non-primary key columns
False
T/F In an E-R diagram, strong entities are represented by double-walled rectangles
False
T/F Most systems developers believe that dat modeling is the least important part of the systems development process.
True
T/F Participation is a relationship may be optional or mandatory
True
T/F Relationships represent action being taken using a verb phrase
False
T/F The degree of a relationship is the number of attributes that are associated with it
False
T/F The intent of a business rule is to break down business structure
False
T/F The purpose of data modeling is to document business rules about processes
False
T/F The relationship among the instances of three entity types is called a unary relationship
True
T/F The relationship between a weak entity type and its owner is an identifying relationship.
Mapping ternary relationships
Ternary relationships are used as many-to-many-to-many relationshipsA new relation is created with foreign keys from the participating entities forming a composite primary key of the new relation
What result is returned from the following query? Select Customer_Name, telephone From customers Where city in ('Boston', 'New York', 'Denver');
The Customer_Name and telephone of all customers living in either Boston, New York, or Denver
What result will the following SQL statement produce? Select Avg(standard_price) as average from Product_V;
The average Standard_Price of all products in Product_V
Identifying Owner
The entity type on which the weak entity type depends.
Discuss the two possible scenarios when mapping an associative entity.
There are two possible cases for associative entities. In one case, you can have an identifier assigned. You would then use this as the primary key. The other case is where the identifier is not assigned. In this case, you would use the primary keys from the other two (or more) relations that are related to the associative entity.
A correlated subquery is executed once for each iteration through the outer loop.
True
Establishing IF-THEN-ELSE logical processing within an SQL statement can now be accomplished by using the CASE keyword in a statement.
True
Expressions are mathematical manipulations of data in a table that may be included as part of the SELECT statement.
True
Figuring out what attributes you want in your query before you write the query will help with query writing.
True
If multiple Boolean operators are used in an SQL statement, NOT is evaluated first, then AND, then OR.
True
In order to find out what customers have not placed an order for a particular item, one might use the NOT qualifier along with the IN qualifier.
True
In order to update data in SQL, one must inform the DBMS which relation, columns, and rows are involved.
True
Joining tables or using a subquery may produce the same result.
True
One of the original purposes of the SQL standard was to provide a vehicle for portability of database definition and application modules between conforming DBMSs.
True
The following query totals sales for each salesperson. Select salesperson_id, sum(sales) from salesperson group by salesperson_id;
True
The joining condition of an equi-join is based upon an equality.
True
The views are created by executing a CREATE VIEW SQL command.
True
Triggers have three parts: the event, the condition, and the action.
True
An alternative name for an attribute is called a(n): A) synonym. B) alias. C) alternate attribute. D) related characteristic.
alias
Domain Constraint
all values in each column must be from the same predefined domain
Relational database
collection of related relations within which each relation has a unique name
________ problems are encountered when removing data with transitive dependencies. A) Insertion B) Modification C) Deletion D) Merging
deletion
A transversal dependency is a functional dependency between two or more nonkey attributes.
false
An anomaly is a type of flaw in the database server.
false
An enterprise key is a foreign key whose value is unique across all relations.
false
An identifier assigned to an associative entity is also called a cross-relation key.
false
Anomalies do not generally arise out of transitive dependencies.
false
CASE tools can model more complex data relationships, such as ternary relationships.
false
Data integrity consists of powerful operations to manipulate data stored in relations.
false
The entity integrity rule states that a primary key attribute can be null.
false
database
final
lets
go
The need to ________ relations commonly occurs when different views need to be integrated. A) metadata B) system C) drop D) merge
merge
________ are anomalies that can be caused by editing data in tables. A) Insertion B) Deletion C) Modification D) Creation
modification
The entity integrity rule states that: A) no primary key attribute can be null. B) referential integrity must be maintained across all entities. C) each entity must have a primary key. D) a primary key must have only one attribute.
no primary key attribute can be null
Relational database constraints
rules that a relational database has to satisfy in order to be valid
Which of the following violates the atomic property of relations? A) Sam B) Hinz C) Sam Hinz D) Atomic
sam hinz
When a regular entity type contains a multivalued attribute, two new relations are created.
true
When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations.
true
When two or more attributes describe the same characteristic of an entity, they are synonyms.
true
Relational schema
visual depiction of the relational database model
A relation that contains minimal redundancy and allows easy use is considered to be: A) clean. B) simple. C) complex. D) well-structured.
well-structured
) A simultaneous relationship among the instances of three entity types is called a(n) ________ relationship. A) ternary B) tertiary C) primary D) binary
A
) Data modeling may be the most important part of the systems development process because: A) data characteristics are important in the design of programs and other systems components. B) the data in a system are generally less complex than processes and play a central role in development. C) data are less stable than processes. D) it is the easiest.
A
A person's name, birthday, and social security number are all examples of: A) attributes. B) entities. C) relationships. D) descriptors.
A
A property or characteristic of an entity type that is of interest to the organization is called a(n): A) attribute. B) coexisting entity. C) relationship. D) cross-function.
A
User-defined transactions can improve system performance because: A) transactions are processed as sets, reducing system overhead. B) transactions are mapped to SQL statements. C) speed is improved due to query optimization. D) all of the above.
A
What does the following SQL command do? insert into Customer_T values (001,'John Smith','231 West St','Boston','MA','02115'); A) Adds a new record to the Customer_T B) Creates the Customer_T table C) Deletes the Customer_T table D) Updates the Customer_T table
A
What does the following SQL statement do? Delete from Customer_T where state = 'HI'; A) Deletes all records from customer_t where the state is equal to HI B) Removes the Customer_T table from the database C) Deletes all records from the Customer_T table D) None of the above
A
What results will be produced by the following SQL query? Select sum(standard_price) as Total_Price from Product_V where Product_Type = 'WOOD'; A) The total price of all products that are of type wood B) The total price of all products C) The Standard_Price of the first wood product in the table D) The Standard_Price of any wood product in the table
A
What will be returned when the following SQL query is executed? Select driver_no, count(*) as num_deliveries from deliveries group by driver_no having count(*) > 2; A) A listing of all drivers who made more than 2 deliveries as well as a count of the number of deliveries B) A listing of all drivers C) A listing of the number of deliveries greater than 2 D) A listing of all drivers who made more than 2 deliveries
A
Which of the following counts ONLY rows that contain a value? A) Count B) Count(*) C) Tally(*) D) Checknum
A
Which of the following is the wildcard operator in SQL statements? A) * B) & C) = D) <>
A
Which of the following questions is answered by the SQL statement? Select Count(Product_Description) from Product_T A)how many products have product descriptions in the product table? B)how many different columns named "product_description" are there in the table Product_T? C)How many products are in the table Product_T?
A
Which of the following terms best describes a class of tools used by end users to analyze data in a data warehouse? A)OLAP B)Data Mart C)DBMS D)CUBE
A
________ is a set of commands used to update and query a database. A) DML B) DDL C) DCL D) DPL
A
________ use the result of the outer query to determine the processing of the inner query. A) Correlated subqueries B) Outer subqueries C) Inner subqueries D) Subqueries
A
_______takes a value of true if a subquery returns an intermediate results table which contains one or more rows A)Exists B)Having C)In D)Extents
A
Explain what a candidate key is and how it might be used.
A candidate key is an attribute or a combination of attributes that uniquely identifies a row in a relation. A candidate key must be nonredundant and must also uniquely identify each row. When we look at functional dependencies and candidate keys, we can always say that a determinant is always a candidate key.
Entity Type
A collection of entities that share common properties or characteristics
What will be returned even the following SQL query is executed? Select driver_no, count(*) as num_deliveries From deliveries Group by driver_no having count(*) > 2
A listing of all drivers who made more than 2 deliveries as well as a count of the number of deliveries
Entity-Relationship Model (E-R Model)
A logical representation of the data for an organization or for a business area, using entities for categories of data and relationships for associations between entities.
Relationship Type
A meaningful association between (or among) entity types
Discuss why it is important to remove multivalued attributes from a relation.
A multivalued attribute is one that can take on more than one value. According to the definition of a relation, there can be no multivalued attributes. The reason for this will be seen later when the schema is normalized. A multivalued attribute can be resolved by creating a separate instance for each value and repeating the data from the non-multivalued attributes.
Discuss the various relational keys.
A primary key uniquely identifies each row of a relation (or table). It can be either a single column or a composite of two or more columns, which is called a composite key. A foreign key allows us to represent the relationship between two tables. A foreign key in one table is generally a reference to a primary key in another table.
Ternary Relationship
A simultaneous relationship among the instances of three entity types
Entity Instance
A single occurrence of an entity type
Business Rule
A statement that defines or constrains some aspect of the business. It is intended to assert business structure or to control or include certain the behavior of the business
Discuss when it is best to create a surrogate key for an associative entity.
A surrogate key should be created when any of the following conditions hold: there is a composite primary key, the natural primary key is inefficient (such as a long name) or the natural primary key is recycled. When you have an associative entity, it is often best to use a surrogate key when you have more than two relations that the associative entity is related to, since the primary key would be a composite of the primary keys of all entities related to the associative entity.
Time Stamp
A time value that is associated with a data value, often indicating when some event occurred that affected the data value
How do you convert weak entities to relations?
A weak entity becomes a relation. However, since a weak entity instance does not exist by itself, we must create a relation with the primary key from the strong relation as the primary key, as well as the identifying attribute.
What is an anomaly, and what are the three types of anomalies?
An anomaly is an error or inconsistency that may result when a user attempts to update a table that contains redundant data. There are three types of anomalies. An insert anomaly occurs when a user attempts to enter new information for part of a table. For example, if we stored customer address with an order. A deletion anomaly occurs when the user wants to delete part of a record but also has to delete related data. A modification anomaly occurs when we have to change the same data in multiple places.
Relationship Instance
An association between (or among) entity instances where each relationship instance associates exactly one entity instance from each participating entity type
Identifier
An attribute (or combination of attributes) whose value distinguishes instances of an entity type
Simple (or atomic) attribute
An attribute that cannot be broken down into smaller components that are meaningful to the organization
Composite Attribute
An attribute that has meaningful component parts (attributes).
Optional Attribute
An attribute that may not have a value for every entity (or relationship) instance with which it is associated
Multivalued attribute
An attribute that may take on more than one value for a given entity (or relationship) instance
Required Attribute
An attribute that must have a volume for every entity (or relationship) instance with which it is associated
Derived Attribute
An attribute whose values can be calculated from related attribute values
Mapping entities with multivalued attributes into relational database constructs
An entity containing the multivalued attribute is mapped without the multi-valued attribute, The multi-valued attribute is mapped as a separate relation that has a column representing the multivalued attribute and a foreign key column referring to the primary key of the relation resulting from the entity itself Both of these columns form a composite primary key for the separate relation
Strong Entity Type
An entity that exists independently of other entity types
Associative Entity
An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances
Weak Entity Type
An entity type whose existence depends on some other entity type
) An attribute that must have a value for every entity (or relationship) instance is a(n): A) composite attribute. B) required attribute. C) optional attribute. D) multivalued attribute.
B
A ________ is a temporary table used in the FROM clause of an SQL query. A) correlated subquery B) derived table C) view table D) none of the above
B
A ________ specifies the number of instances of one entity that can be associated with each instance of another entity. A) degree B) cardinality constraint C) counter constraint D) limit
B
A ________ view is materialized when referenced. A) virtual B) dynamic C) materialized D) base
B
A fact is an association between two or more: A) words. B) terms. C) facts. D) nuggets.
B
A join operation: A) brings together data from two different fields. B) causes two tables with a common domain to be combined into a single table or view. C) causes two disparate tables to be combined into a single table or view. D) is used to combine indexing operations.
B
A join that is based upon equality between values in two common columns with the same name and where one duplicate column has been removed is called a(n): A) equi-join. B) natural join. C) multivariate join. D) inner join
B
A mutually exclusive relationship is one in which: A) an entity instance can participate in many different relationships. B) an entity instance can participate in only one of several alternative relationships. C) an entity instance can not participate in a relationship with another entity instance. D) none of the above.
B
A single value returned from an SQL query that includes an aggregate function is called a(n): A) agate. B) scalar aggregate. C) vector aggregate. D) summation.
B
A student can attend five classes, each with a different professor. Each professor has 30 students. The relationship of students to professors is a ________ relationship. A) one-to-one B) many-to-many C) one-to-many D) strong
B
A type of join where a table is joined to itself is called a(n): A) unary join. B) self-join. C) unnatural join. D) pinned join.
B
A type of query that is placed within a WHERE or HAVING clause of another query is called a: A) master query. B) subquery. C) superquery. D) multi-query
B
A value that indicates the date or time of a data value is called a(n): A) value stamp. B) time stamp. C) checkpoint. D) check counter
B
A(n) ________ is the relationship between a weak entity type and its owner. A) member chain B) identifying relationship C) jump path D) chain link
B
All of the following are guidelines for better query design EXCEPT: A) understand how indexes are used in query processing. B) use a lot of self-joins. C) write simple queries. D) retrieve on the data that you need.
B
Explicit commands to manage transactions are needed when: A) a transaction consists of just one SQL command. B) multiple SQL commands must be run as part of a transaction. C) autocommit is set to off. D) none of the above
B
Extensions defined in SQL-99 that include the capability to create and drop modules of code stored in the database schema across user sessions are called: A) stored procedures. B) Persistent Stored Modules. C) flow control modules. D) none of the above.
B
Given a table named store with 5 fields: store_id, address, city, state, zipcode, why would the following insert command not work? insert into store values ('234 Park Street') A) It would work just fine. B) You must specify the fields to insert if you are only inserting some of the fields. C) There is no table keyword. D) None of the above.
B
In a SQL statement, which of the following parts states the conditions for row selection? A) From B)Where C)Select D)Group by
B
What results would the following SQL statement produce? select owner, table_name from dba_tables where table_name = 'CUSTOMER'; A) A listing of all customers in the customer table B) A listing of the owner of the customer table C) A listing of the owner of the customer table as well as customers D) An error message
B
What will be returned when the following SQL statement is executed? Select driver_no, count(*) as num_deliveries from deliveries where state = 'MA' group by driver_no; A) A listing of all drivers who made deliveries to state = 'MA', sorted by driver number B) A listing of each driver who made deliveries to state = 'MA' as well as the number of deliveries that each driver has made to that state C) A count of all of the deliveries made to state = 'MA' by all drivers D) None of the above
B
What will be returned when the following SQL statement is executed? Select driver_no,count(*) as num_deliveries from deliveries group by driver_no; A) A listing of all drivers, sorted by driver number B) A listing of each driver as well as the number of deliveries that he or she has made C) A count of all of the deliveries made by all drivers D) None of the above
B
Which of the following can produce scalar and vector aggregates? A) ORDER BY B) GROUP BY C) HAVING D) SORT
B
Which of the following is a technique for optimizing the internal performance of the relational data model? A) Avoiding indexes on secondary keys B) Clustering data C) Not reporting statistics to save machine resources D) Using random index organizations
B
Which of the following is the wildcard operator in SQL statements? A) < > B) * C) = D) &
B
While triggers run automatically, ________ do not and have to be called. A) trapdoors B) routines C) selects D) updates
B
) An entity type name should be all of the following EXCEPT: A) concise. B) specific to the organization. C) as short as possible. D) a singular noun.
C
) Which of the following is NOT a characteristic of a good business rule? A) Declarative B) Atomic C) Inconsistent D) Expressible
C
A named set of SQL statements that are considered when a data modification occurs are called: A) stored procedures. B) treatments. C) triggers. D) trapdoors.
C
The command for creating a database is: A) create table. B) create view. C) create schema. D) create authorization.
C
The number of entity types that participate in a relationship is called the: A) number. B) identifying characteristic. C) degree. D) counter.
C
What does the following SQL statement do? Alter Table Customer_T Add (Type Varchar (2)); A) Alters the Customer_T table to accept Type 2 Varchars B) Alters the Customer_T table to be a Type 2 Varchar C) Alters the Customer_T table, and adds a field called "Type" D) Alters the Customer_T table by adding a 2-byte field called "Varchar"
C
What result set will the following query return? Select Item_No, description from item where weight > 100 and weight < 200; A) The Item_No and description for all items weighing less than 100 B) The Item_No for all items weighing between 101 and 199 C) The Item_No and description for all items weighing between 101 and 199 D) The Item_No for all items weighing more than 200
C
What will result from the following SQL Select statement? Select min(Product_Description) from Product_V; A) The minimum value of Product_Description will be displayed. B) An error message will be generated. C) The first product description alphabetically in Product_V will be shown. D) None of the above
C
When we consider data in the data warehouse to be time variant, we mean: A)that the time of storage varies B)that there is a time delay between when data are posted and when we report on the data C)data in the warehouse contain a time dimension so that they may be used to study trends and changes D)none of the above
C
Which of the following are most likely to be enforced by a database? A) business organization charts B)Business problems C) Business Rules D) Business Requirements
C
Which of the following finds all groups meeting stated conditions? A) Select B) Where C) Having D) Find
C
________ differs from array because it can contain duplicates. A) BIGINT B) XML C) MULTISET D) TABLE
C
The union clause is used to
Combine the output from multiple queries into a single result table
A new set of analytical functions added in SQL:2008 is referred to as: A) OLAF functions. B) MOLAP functions. C) average functions. D) OLAP functions.
D
A procedure is: A) stored within the database. B) given a unique name. C) called by name. D) all of the above.
D
TQM stands for: A)Thomas Quinn Mann, a famous data quality innovator B)transforming quality management C)total quality manipulation D)total quality management
D
Which of the following conditions should exist if an associative entity is to be created? A) All the relationships for the participating entities are many-to-many. B) The new associative entity has independent meaning. C) The new associative entity participates in independent relationships. D) All of the above
D
Which of the following criteria should be considered when selecting an identifier? A) Choose an identifier that is stable. B) Choose an identifier that will not be null. C) Choose an identifier that doesn't have large composite attributes. D) All of the above.
D
User-defined constraints
Database constraints that are added by the database designer
Discuss the two major occasions when you benefit from using normalization.
During logical database design, normalization is used as a check and balance to make sure that your E-R diagram is correct as well as your relational schema before doing physical design. Another occasion when you benefit is reverse-engineering an older system, since many of the tables and user views are redundant.
Mapping entities into relations
Each regular entity becomes a relation, Each regular attribute of a regular entity becomes a column of the newly created relation, If an entity has a single unique attribute, then that attribute becomes the primary key in the resulting mapped relation
Discuss how you would map a regular entity to a relation.
Each regular entity is transformed into a relation. There are a couple of things that need to be done with some special types of attributes. Composite attributes are broken down into their individual components. Multivalued attributes are broken down into separate relations. For example, if there was a multivalued skill attribute, this would become a skill relation. Also, we ignore derived attributes.
A catalog is the structure that contains object descriptions created by a user.
False
A database is maintained and queried using the data mapping language (DML).
False
A function has only input parameters but can return multiple values.
False
A referential integrity constraint specifies that the existence of an attribute in one table depends upon the existence of a foreign key in the same or another table.
False
A routine is a named set of SQL statements that are considered when a data modification occurs.
False
A single value returned from an SQL query that includes an aggregate function is called a vector aggregate.
False
A subquery in which processing the inner query depends on data from the outer query is called a codependent query.
False
An equi-join is a join in which one of the duplicate columns is eliminated in the result table.
False
Combining a table with itself results in a faster query.
False
Mapping M:N unary relationships
In addition to the relation representing the entity involved in a unary M:N relationship, another relation is created to represent the M:N relationship itself, This new relation has two foreign keys, both of them corresponding to the primary key of the relation representing the entity involved in the unary M:N relationship, Each of the foreign keys is used as a part of the composite primary key of the new relation
Union join
Includes all data from each table that was joined
relational DBMS (RDBMS)
Most contemporary commercial DBMS software packages, are relational DBMS (RDBMS) software packages
Mapping entities with optional attributes into relations
Optional attribute of an entity is mapped as an optional column
What does the following SQL statement do? Select * From Customwr Where Cust_Type = "Best"
Selects all the fields from the customer table for each row with a customer labeled "Best"
False
T/F A Cardinality constraint tells what kinds of properties are associated with an entity
True
T/F A business rule is a statement that defines or constrains some aspect of the business
True
T/F A multivalued attribute may take on more thank once value for a particular entity instance
True
T/F A single occurrence of an entity is called an entity instance
False
T/F A ternary relationship is equivalent to three binary relationships
True
T/F A time stamp is a time value that is associated with a data value
True
T/F An attribute whose values can be calculated from related attribute values is called a derived attribute.
True
T/F An entity is a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data
True
T/F Data modeling is about documenting rules and policies of an organization that govern data.
True
T/F Data names should always relate to business characteristics
True
T/F In an E-R diagram, an associative entity is represented by a rounded rectangle
True
T/F One reason to use an associative entity is if the associative entity has one or more attributes in addition to the identifier
True
T/F When choosing an identifier, choose one that will not change its value often
True
T/F Τhe E-R model is used to construct a conceptual model
Discuss how to map a unary one-to-many relationship.
The entity type in the unary relationship is mapped to a relation in the same way as we did for a relation. We next add a foreign key attribute, which maps back to the primary key. This is called a recursive foreign key. So, if we had a relation such as a person supervises one or more persons, the person_id would be a primary key and then there would be a supervisor id which points back to the person_id.
Implicit constraints
The implicit relational database model rules that a relational database must satisfy in order to be valid
Maximum Cardinality
The maximum number of instances of one entity that may be associated with each instance of another entity.
Minimum Cardinality
The minimum number of instances of one entity that may be associated with each instance of another entity
Degree
The number of entity types that participate in a relationship
Mapping 1:M unary relationships
The relation mapped from an entity involved in a 1:M unary relationship contains a foreign key that corresponds to its own primary key
Mapping 1:M relationships
The relation mapped from the entity on the M side of the 1:M relationship has a foreign key that corresponds to the primary key of the relation mapped from the 1 side of the 1:M relationship
Identifying Relationship
The relationship between a weak entity type and its owner
Discuss the types of integrity constraints.
The three major types of integrity constraints are domain constraints, entity integrity and referential integrity. A domain is a set of attributes assigned to an attribute and consists of the domain name, data type, size and allowable values. The entity integrity rule is designed to ensure that every relation has a primary key and that the data values for the primary key are valid (in particular, not null). The referential integrity constraint is a rule that maintains consistency among the rows of two relations. If there is a foreign key in one relation, there must be a matching primary key in the other relation or the foreign key must be null.
) The following two SQL statements will produce the same results. Select last_name, first_name from customer where credit_limit > 99 and credit_limit < 10001; Select last_name, first_name from customer where credit_limit between 100 and 10000;
True
Applications can be moved from one machine to another when each machine uses SQL
True
Constraints are a special case of triggers.
True
RDBMSs store database definition information in system-created tables which can be considered a data dictionary.
True
SQL is both an American and international standard for database access.
True
SQL statements can be included in another language, such as C or Java.
True
SQL:2008 allows one to calculate linear regressions, moving averages and correlations without moving the data outside of the database.
True
Some DBMS can handle graphic data types as well as text and numbers.
True
The ALTER TABLE command is used to change a table definition.
True
The FROM clause is the first statement processed in an SQL command.
True
The ORDER BY clause sorts the final results rows in ascending or descending order.
True
The SQL command used to populate tables is the INSERT command.
True
The UNION clause is used to combine the output from multiple queries into a single result table.
True
The WHERE clause includes the conditions for row selection within a single table or view and the conditions between tables or views for joining.
True
When EXISTS or NOT EXISTS is used in a subquery, the select list of the subquery will usually just select all columns as a placeholder because it doesn't matter which columns are returned.
True
When a GROUP BY clause is included in an SQL statement, only those columns with a single value for each group can be included.
True
When creating tables, it's important to decide which columns will allow null values before the table is created.
True
Discuss how to map a unary many-to-many relationship.
Two relations are created. One represents the entity type in the relationship, and the other is an associative relation to represent the M:N relationship. The primary key of the associative relation consists of two attributes which take their value from the primary key of the other relation.
Business rules
User defined constraints that specify restrictions on databases that are not a part of the standard notation for creating ER diagrams
Discuss why it is a good idea to create an instance of your relational schema with sample data.
Using sample data allows you to test any assumptions that you may have regarding the design. In addition, it provides a convenient way to check the accuracy of your design and helps to improve communication with users. A final benefit is that you will be able to develop prototype applications and sample queries with the data.
Explain how subtype/supertype relationships are converted to relations.
When we have a supertype/subtype relationship, we need to assign one entity for the supertype and one for each subtype. The supertype has all attributes common to all subtypes as well as a primary key. Each subtype relation has the primary key of the supertype as well as any attributes that are specific to that subtype. Finally, we assign one or more attributes to the supertype to function as subtype discriminators.
Composite primary key
a primary key that is composed of multiple columns
The normal form which removes any remaining functional dependencies because there was more than one primary key for the same nonkeys is called: A) fifth normal form. B) fourth normal form. C) Boyce-Codd normal form. D) sixth normal form.
boyce-codd normal form
Primary key
column (or a set of columns) whose value is unique for each row, Each relation must have a primary key, The name of the primary key column is underlined in order to distinguish it from the other columns in the relation
Foreign key
column in a relation that refers to a primary key column in another (referred) relation
A primary key that consists of more than one attribute is called a: A) foreign key. B) composite key. C) multivalued key. D) cardinal key.
composite key
________ is a component of the relational data model included to specify business rules to maintain the integrity of data when they are manipulated. A) Business rule constraint B) Data integrity C) Business integrity D) Data structure
data integrity
A nonkey attribute is also called a(n): A) column. B) unimportant datum. C) descriptor. D) address.
descriptor
The attribute on the left-hand side of the arrow in a functional dependency is the: A) candidate key. B) determinant. C) foreign key. D) primary key.
determinant
Primary key Constraint
each relation must have a primary key, which is a column (or a set of columns) whose value is unique for each row
Autonumber data type option
enables automatic generation of consecutive numeric data values in a column
A primary key whose value is unique across all relations is called a(n): A) global primary key. B) inter-table primary key. C) enterprise key. D) foreign global key.
enterprise key
The ________ states that no primary key attribute may be null. A) referential integrity constraint B) entity integrity rule C) partial specialization rule D) range domain rule
entity integrity rule
62) When transforming a weak entity, one should create one relation with both the attributes of the strong entity and the attributes of the weak entity.
false
A co-dependency is a constraint between two attributes or two sets of attributes.
false
A composite key consists of only one attribute.
false
A foreign key is a primary key of a relation that also is a primary key in another relation.
false
A relation is in first normal form if it has no more than one multivalued attribute.
false
A synonym is an attribute that may have more than one meaning.
false
In the relational data model, associations between tables are defined through the use of primary keys.
false
The primary key of the many side migrates to the one side when transforming a one-to-many relationship.
false
The relational data model does, at this time, directly support subtype/supertype relationships.
false
The truncate table statement in SQL creates a new table.
false
There can be multivalued attributes in a relation.
false
Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence.
false
When all multivalued attributes have been removed from a relation, it is said to be in: A) first normal form. B) second normal form. C) Boyce-Codd normal form. D) third normal form.
first normal form
An attribute in a relation of a database that serves as the primary key of another relation in the same database is called a: A) link attribute. B) link key. C) foreign key. D) foreign attribute.
foreign key
The normal form which deals with multivalued dependencies is called: A) fifth normal form. B) fourth normal form. C) Boyce-Codd normal form. D) sixth normal form.
fourth normal form
A constraint between two attributes is called a(n): A) functional relation. B) attribute dependency. C) functional dependency. D) functional relation constraint.
functional dependency
When transforming a one-to-one relationship, a new relation is always created.
galse
An attribute that may have more than one meaning is called a(n): A) homonym. B) alias. C) double defined attribute. D) synonym.
homonym
Entity integrity constraint
in a relational table, no primary key column can have null (empty) values
Mapping 1:1 relationships
mapped the same as 1:M relationships primary key of another resulting relation, One of the mapped relations is chosen to have a foreign key referring to the primary key of the other mapped relation, In cases when there is no particular advantage in choosing which resulting relation will include a foreign key, the choice can be arbitrary, In other cases one choice can be more efficient than the other
All of the following are the main goals of normalization EXCEPT: A) minimize data redundancy. B) simplify the enforcement of referential integrity. C) maximize storage space. D) make it easier to maintain data.
maximize storage space
A rule that states that each foreign key value must match a primary key value in the other relation is called the: A) referential integrity constraint. B) key match rule. C) entity key group rule. D) foreign/primary match rule.
referential integrity constraint
A two-dimensional table of data sometimes is called a: A) group. B) set. C) declaration. D) relation.
relation
Which of the following is NOT a reason to create an instance of a relational schema with sample data? A) Sample data can be used to improve user communications. B) Sample data can be used for prototype generation. C) Sample data can reverse database implementation errors. D) Sample data provide a convenient way to check the accuracy of your design.
sample data can reverse database implementation errors
A relation that contains no multivalued attributes and has nonkey attributes solely dependent on the primary key but contains transitive dependencies is in which normal form? A) First B) Second C) Third D) Fourth
second
Two or more attributes having different names but the same meaning are called: A) homonyms. B) aliases. C) synonyms. D) alternate attributes.
synonyms
Relation
table in a relational database: A table containing rows and columns, The main construct in the relational database model, Every relation is a table, not every table is a relation
A functional dependency between two or more nonkey attributes is called a: A) partial functional dependency. B) partial nonkey dependency. C) transitive dependency. D) partial transitive dependency.
transitive dependency
A candidate key is an attribute, or combination of attributes, that uniquely identifies a row in a relation.
true
A primary key is an attribute that uniquely identifies each row in a relation.
true
A referential integrity constraint is a rule that maintains consistency among the rows of two relations.
true
A relation in fifth normal form may not contain any anomalies.
true
A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
true
All values that appear in a column of a relation must be taken from the same domain.
true
Data structures include data organized in the form of tables with rows and columns.
true
If an identifier is not assigned, the default primary key for an associative relation consists of the two primary key attributes from the other two relations.
true
One property of a relation is that each attribute within a relation has a unique name.
true
Sample data are useful for developing prototype applications and for testing queries.
true
The allowable range of values for a given attribute is part of the domain constraint.
true
An entity that associates the instances of one or more entity types and contains attributes specific to the relationships is called a(n): A) associative entity. B) connecting entity. C) intersectional entity. D) all of the above.
A
Customers, cars, and parts are examples of: A) entities. B) attributes. C) cardinals. D) relationships.
A
Dynamic SQL: A) is used to generate appropriate SQL code on the fly as an application is processing. B) is quite volatile. C) is not used widely on the Internet. D) creates a less flexible application
A
Embedded SQL consists of: A) hard-coded SQL statements included in a program written in another language. B) SQL encapsulated inside of other SQL statements. C) SQL written into a front-end application. D) SQL translated to a lower-level language.
A
In SQL, a(n) ________ subquery is a type of subquery in which processing the inner query depends on data from the outer query. A) correlated B) paired C) natural D) inner
A
In an E-R diagram, there are ________ business rule(s) for every relationship. A) two B) three C) one D) none
A
Multiple values returned from an SQL query that includes an aggregate function are called: A) vector aggregates. B) scalar aggregates. C) agates. D) summations
A
The MERGE command: A) allows one to combine the INSERT and UPDATE operations. B) allows one to combine the INSERT and DELETE operations. C) joins 2 tables together. D) none of the above.
A
The UNION clause is used to: A) combine the output from multiple queries into a single result table. B) join two tables together to form one table. C) find all rows that do not match in two tables. D) none of the above.
A
The ________ DBA view shows information about all users of the database in Oracle. A) DBA_USERS B) USERS C) DBA_VIEWS D) DBA_INDEXES
A
To get all the customers from Hawaii sorted together, which of the following would be used? A)order by B)having C)group by D)sort
A
To get all the customers from Hawaii sorted together, which of the following would be used? A) ORDER BY B) GROUP BY C) HAVING D) SORT
A
What does the following SQL statement do? Select * From Customer Where Cust_Type = "Best" A) Selects all the fields from the Customer table for each row with a customer labeled "Best" B) Selects the "*" field from the Customer table for each row with a customer labeled "Best" C) Selects fields with a "*" in them from the Customer table D) Selects all the fields from the Customer table for each row with a customer labeled "*"
A
Entity-Relationship Diagram (E-R Diagram)
A graphical representation of an entity-relationship model
Outer join
A join in which rows that do not have matching values in common columns are nonetheless included in the result table (As opposed to inner join, in which rows must have matching values in order to appear in the result table)
Equi-join
A join in which the joining condition is based on equality between values in the common columns; common columns appear redundantly in the result table
Entity
A person, a place, an object, an event, or a concept in the user environment about which the organization wishes to maintain data
All of the following are new data types added in SQL:200n EXCEPT: A) BIGINT. B) BIT. C) MULTISET. D) XML.
B
All of the following are tasks of data cleaning EXCEPT: A) decoding data to make them understandable for data warehousing applications B) creating foreign keys C)adding time stamps to distinguish values for the same attribute over time D)Generating primary keys for each row of a table
B
An attribute that uniquely identifies an entity and consists of a composite attribute is called a(n): A) composite attribute. B) composite identifier. C) identifying attribute. D) relationship identifier
B
An entity type whose existence depends on another entity type is called a ________ entity. A) strong B) weak C) codependent D) variant
B
Any create command may be reversed by using a ________ command. A) truncate B) drop C) delete D) unpack
B
As a general rule, which of the following data-related IT positions would pay the most? A)data dictionary analyst B)Database Administrator C)Data repository manager D)Data Analyst
B
DDL is typically used during which phases of the development process? A) Implementation B) Physical design C) Analysis D) All of the above
B
In order for two queries to be UNION-compatible, they must: A) both have the same number of lines in their SQL statements. B) both output compatible data types for each column and return the same number of rows. C) both return at least one row. D) all of the above.
B
In order to embed SQL inside of another language, the ________ statement must be placed before the SQL in the host language. A) GET SQL B) EXEC SQL C) RUN SQL D) SQL SQL
B
One major advantage of the outer join is that: A) information is easily accessible. B) information is not lost. C) the query is easier to write. D) all of the above.
B
The SQL command ________ adds one or more new columns to a table. A) create table B) alter table C) create view D) create relationship
B
The ________ is the structure that contains descriptions of objects such as tables and views created by users. A) SQL B) schema C) catalog D) master view
B
The first in a series of steps to follow when creating a table is to: A) identify columns that must be unique. B) identify each attribute and its characteristics. C) create an index. D) identify columns that must be null
B
The logical representation of an organization's data is called a(n): A) database model. B) entity-relationship model. C) relationship systems design. D) database entity diagram
B
The process of combining data from various sources into a single table or view is called: A)extracting B)joining C)updating D)selecting
B
To eliminate duplicate rows in a query, the ________ qualifier is used in the SQL Select command. A) alter B) distinct C) check D) specific
B
To eliminate duplicate rows in a query, the____qualifier is used in the SQL Select command A)alter B)distinct C)check D)specific
B
What does the following SQL statement do? Update Product_T Set Unit_Price = 775 Where Product_ID = 7 A) Changes the price of a unit called Product_T to 7 B) Changes the unit price of Product 7 to 775 C) Changes the length of the Unit_Price field to 775 D) Updates the Product_T table to have a unit price of 775
B
What result set is returned from the following query? Select Customer_Name, telephone from customers where city in ('Boston','New York','Denver'); A) The Customer_Name and telephone of all customers B) The Customer_Name and telephone of all customers living in either Boston, New York or Denver C) The Customer_Name and telephone of all customers living in Boston and New York and Denver D) The Customer_Name of all customers living in Boston, New York or Denver
B
Which of the following questions is answered by the SQL statement? Select Count (Product_Description) from Product_T; A) How many products are in the table Product_T? B) How many products have product descriptions in the Product Table? C) How many characters are in the field name "Product_Description"? D) How many different columns named "Product_Description" are there in table Product_T?
B
Which of the following will produce the minimum of all standard prices? A) Select standard_price from Product_V where Standard_Price = min; B) Select min(standard_price) from Product_V; C) Select Standard_Price from min(Product_V); D) Select min(Standard_Price) from Product_V where Standard_Price = min(Standard_Price);
B
) In which of the following situations would one have to use an outer join in order to obtain the desired results? A) A report is desired that lists all customers who placed an order. B) A report is desired that lists all customers and the total of their orders. C) A report is desired that lists all customers, the total of their orders during the most recent month, and includes customers who did not place an order during the month (their total will be zero). D) There is never a situation that requires only an outer join.
C
A join in which rows that do not have matching values in common columns are still included in the result table is called a(n): A) natural join. B) equi-join. C) outer join. D) union join.
C
A join operation: A) causes two disparate tables to be combined into a single table or view B)Brings together data from two different fields C) causes two tables with a common domain to be combined into a single table or view D) is used to combine indexing operations
C
A______is a temporary table used in the FROM clause of an SQL query A) view table B) correlated subquery C) derived table D) none of the above
C
All of the following are part of the coding structure for triggers EXCEPT: A) event. B) condition. C) selection. D) action.
C
An attribute of an entity that must have a value for each entity instance is a(n): A) optional attribute. B) composite attribute. C) required attribute. D) fuzzy attribute.
C
An attribute that can be broken down into smaller parts is called a(n) ________ attribute. A) associative B) simple C) composite D) complex
C
An interactive command that can be used to dynamically control a user session for appropriate integrity measures is: A) rollback. B) rollforward. C) set autocommit. D) expunge.
C
EXISTS will take a value of ________ if the subquery returns an intermediate results table which contains one or more rows. A) FALSE B) 1 C) TRUE D) undefined
C
Establishing IF-THEN-ELSE logical processing within an SQL statement can be accomplished by: A) using the if-then-else construct. B) using the immediate if statement. C) using the CASE keyword in a statement. D) using a subquery.
C
In an SQL statement, which of the following parts states the conditions for row selection? A) Select B) From C) Where D) Group By
C
SQL provides the ________ technique, which involves placing an inner query within the WHERE or HAVING clause of an outer query. A) grouping B) joining C) subquery D) union
C
SQL-invoked routines can be: A) procedures. B) functions. C) all of the above. D) none of the above.
C
The SQL command ________ defines a logical table from one or more tables or views. A) create table B) alter table C) create view D) create relationship
C
Which of the following is true of the order in which SQL statements are evaluated? A) The SELECT clause is always processed first. B) The SELECT clause is always processed last. C) The SELECT clause is processed before the ORDER BY clause. D) The GROUP BY clause is processed before the WHERE clause
C
________ is a set of commands used to control a database, which includes security. A) DML B) DDL C) DCL D) DPL
C
________ takes a value of true if a subquery returns an intermediate results table which contains one or more rows. A) IN B) HAVING C) EXISTS D) EXTENTS
C
______duplicates data across databases A) a replication server B)data duplication C)data propagation D)redundant replication
C
data governance can be defined as: A)a government task force for defining data quality B)a means to slow down the speed of data C)high level organizational groups and processes that oversee data stewardship D)none of the above
C
A relationship between the instances of a single entity type is called a(n) ________ relationship. A) ternary B) primary C) binary D) unary
D
A relationship where the minimum and maximum cardinality are both one is a(n) ________ relationship. A) optional B) unidirectional C) mandatory link D) mandatory one
D
A view may not be updated directly if it contains: A) the DISTINCT keyword. B) derived columns and expressions in the SELECT clause. C) uses the GROUP BY or HAVING clause. D) all of the above.
D
All of the following are advantages of SQL-invoked routines EXCEPT: A) flexibility. B) efficiency. C) sharability. D) security.
D
An attribute that can be calculated from related attribute values is called a(n) ________ attribute. A) simple B) composite C) multivalued D) derived
D
An operation to join a table to itself is called a: A) sufficient-join. B) inner join. C) outer join. D) self-join.
D
If the DBA wishes to describe all tables in the database, which data dictionary view should be accessed in Oracle? A) dba_tab_privs B) dba_tab_comments C) dba_table_label D) dba_tables
D
Loading data into a data warehouse involves: A)updating existing rows with new data B)purging data that have become obsolete or were incorrectly loaded C)appending new rows to the tables in the warehouse D)all of the above
D
The ________ clause is used to combine the output from multiple queries into a single result table. A) INTERSECT B) DIVIDE C) COLLATE D) UNION
D
The benefits of a standardized relational language include: A) application longevity. B) reduced training costs. C) cross-system communication. D) all of the above.
D
The common types of entities are: A) strong entities. B) weak entities. C) associative entities. D) all of the above.
D
The most commonly used form of join operation is the: A) outer join. B) union join. C) equi-join. D) natural join.
D
User-defined data types: A) can be a subclass of a standard type. B) can behave as an object. C) can have defined functions and methods. D) can have all of the above.
D
What result set will the following query return? Select Item_No from Order_V where quantity > 10; A) The Item_No of all orders that had more than 10 items B) The Order_Id of all orders that had more than one item C) The Order_Id of all orders that had more than 10 items D) The Item_No of all orders that had 10 or more items
D
Which of the following data-mining applications identifies customers for promotional activity? A)population profiling B)usage analysis C)product affinity D)Target marketing
D
Which of the following is NOT a good characteristic of a data name? A) Relates to business characteristics B) Readable C) Repeatable D) Relates to a technical characteristic of the system
D
Which of the following is a purpose of the SQL standard? A) To specify syntax and semantics of SQL data definition and manipulation B) To specify minimal and complete standards, which permit different degrees of adoption in products C) To define the data structures and basic operations for SQL databases D) All of the above
D
Which of the following is an entity type on which a strong entity depends? A) Owner B) Member C) Attribute D) None of the above
D
Mapping entities with composite attributes into relations
Each component of a composite attribute is mapped as a column of a relation. The composite attribute itself does not appear in the mapped relation
Count(*) tallies only those rows that contain a value, while Count counts all rows.
False
DBA_USERS contains comments on all tables in an Oracle database.
False
DBA_USERS contains comments on all tables in an oracle database(T/F)
False
DCL is used to update the database with new records.
False
Indexes generally slow down access speed in most RDMS.
False
It is better not to have a result set identified before writing GROUP BY and HAVING clauses for a query.
False
MULTISET is similar to the table datatype.
False
Materialized views are stored on disk and are never refreshed.
False
One major disadvantage of the outer join is that information is easily lost.
False
Persistent Sorted Modules are extensions defined in SQL-99 that include the capability to create and drop modules of code stored in the database schema across user sessions.
False
The comparison operators = and != are used to establish a range of values.
False
The following two SQL statements will produce different results. Select last_name, first_name from customer where state = 'MA' or state = 'NY' or state = 'NJ' or state = 'NH' or state = 'CT'; Select last_name, first_name from customer where state in ('MA','NY','NJ','NH','CT');
False
The natural join is very rarely used (T/F)
False
When the SELECT clause in the create view statement contains the keyword DISTINCT, the view can be used to update data.
False
Mapping M:N relationships
In addition to the two relations representing the two entities involved in the M:N relationship, another relation is created to represent the M:N relationship itself, This new relation has two foreign keys, corresponding to the primary keys of the two relations representing the two entities involved in the M:N relationship, The two foreign keys form the composite primary key of the new relation
True
T/F A good data definition is always accompanied by diagrams, such as the entity-relationship diagram
List and explain 1st, 2nd, 3rd, BCNF, 4th, and 5th normal forms.
There are six different normal forms, all of which build upon each other. When a relation is in first normal form, all repeating groups have been removed. Second normal form means that any partial functional dependencies have been removed. A partial functional dependency occurs when a primary key is a composite key and a nonkey attribute is dependent upon part of the key. A relation is in third normal form when all transitive dependencies have been resolved. A transitive dependency occurs when one nonkey attribute is dependent upon another nonkey attribute. Boyce-Codd normal form removes any further dependencies that may result from anomalies. A relation is in fourth normal form when any dependencies from multivalued attributes have been removed. Fifth normal form removes any further anomalies.
A database table is defined using the data definition language (DDL).
True
A join in which the joining condition is based on equality between values in the common column is called a(n) equi-join.
True
A major benefit of SQL as a standard is reduced training costs
True
A natural join is the same as an equi-join, except that it is performed over matching columns that have been defined with the same name, and one of the duplicate columns is eliminated (T/F)
True
A natural join is the same as an equi-join, except that it is performed over matching columns that have been defined with the same name, and one of the duplicate columns is eliminated.
True
A procedure is run by calling it by its name.
True
A transaction is the complete set of closely related update commands that must all be done, or none of them done, for the database to remain valid.
True
A trigger is a named set of SQL statements that are considered when a data modification occurs.
True
Adding the DISTINCT keyword to a query eliminates duplicates.
True
An SQL query that implements an outer join will return rows that do not have matching values in common columns
True
An insert command does not need to have the fields listed.
True
Correlated subqueries are less efficient than queries that do not use nesting.
True
Persistent Stored Modules are extensions defined in SQL:1999 that include the capability to add and drop modules of code.
True
The WHERE clause is always processed before the GROUP BY clause when both occur in a SELECT statement.
True
The advantages of SQL-invoked routines are flexibility, efficiency, shareability and applicability.
True
The asterisk (*) wildcard designator can be used to select all fields from a table as well as in WHERE clauses when an exact match is not possible.
True
The content of dynamic views is generated when they are referenced
True
The following SQL statement is an example of a correlated subquery. select first_name, last_name, total_sales from salesman s1 where total_sales > all (select total_sales from salesman s2 where s1.salesman_id != s2.salesman_id);
True
The following queries produce the same results. select customer_name, customer_city from customer, salesman where customer.salesman_id = salesman.salesman_id and salesman.lname = 'SMITH'; select customer_name, customer_city from customer where customer.salesman_id = (select salesman_id from salesman where lname = 'SMITH');
True
Mapping unary relationships
Unary relationships in ER diagrams are mapped in the same way as binary relationships
Mapping weak entities
Weak entities are mapped in a same way as regular entities with one addition: The resulting relation has a composite primary key that is composed of the partial identifier and the foreign key corresponding to the primary key of the owner entity
Given a table named store with 5 fields: store_id, address, city, state, zip code, why would the following insert command not work? Insert into store values ('234 Park Street')
You must specifiy the fields to insert if you are only inserting some of the fields(they didnt even enter zip code, state, or city)
In the SQL language, the ________ statement is used to make table definitions. A) create session B) create table C) create index D) select
create table
When a regular entity type contains a multivalued attribute, one must: A) create a single relation with multiple lines for each instance of the multivalued attribute. B) create two new relations, one containing the multivalued attribute. C) create two new relations, both containing the multivalued attribute. D) delete the relation and start over.
create two new relations, one containing the multivalued attribute
When transforming a unary many-to-many relationship to relations, a recursive foreign key is used.
false
A domain definition consists of all of the following components EXCEPT: A) domain name. B) data type. C) integrity constraints. D) size.
integrity constraints
Relational database model
logical database model that represents a database as a collection of related tables
A form of database specification which maps conceptual requirements is called: A) logical specifications. B) response specifications. C) security specifications. D) physical specifications.
logical specifications
Which of the following are properties of relations? A) Each attribute has the same name. B) No two rows in a relation are identical. C) There are multivalued attributes in a relation. D) All columns are numeric.
no two rows in a relation are identical
Understanding the steps involved in transforming EER diagrams into relations is important because: A) one must be able to check the output of a CASE tool. B) there are rarely legitimate alternatives from which to choose. C) CASE tools can model any situation. D) CASE tools model hypothetical business problems.
one must be able to check the output of a CASE tool
A functional dependency in which one or more nonkey attributes are functionally dependent on part, but not all, of the primary key is called a ________ dependency. A) partial key-based B) partial functional C) cross key D) merged relation
partial function
________ database specification indicates all the parameters for data storage that are then input to database implementation. A) Logical B) Physical C) Schematic D) Conceptual
physical
An attribute (or attributes) that uniquely identifies each row in a relation is called a: A) column. B) foreign field. C) primary key. D) duplicate key.
primary key
Designer-created primary key
primary key column, not called for by the original requirements, added to a table by the database designer Often used in conjunction with the autonumber data type option
Relation
table in a relational database: In order for a table to be a relation the following conditions must hold: Each column must have a name (within one table, each column name must be unique), Within one table, each row must be unique, Within each row, each value in each column must be single valued (multiple values of the content represented by the column are not allowed in any rows of the table), All values in each column must be from the same (predefined) domain, Order of columns is irrelevant, Order of rows is irrelevant
Data is represented in the form of: A) data trees. B) tables. C) data notes. D) chairs.
tables
A candidate key must satisfy all of the following conditions EXCEPT: A) the key must uniquely identify the row. B) the key must indicate the row's position in the table. C) the key must be nonredundant. D) each nonkey attribute is functionally dependent upon it.
the key must indicate the row's position in the table
A cascading delete removes all records in other tables associated with the record to be deleted.
true
A partial functional dependency is a functional dependency in which one or more nonkey attributes are functionally dependent on part (but not all) of the primary key.
true
The columns of a relation can be interchanged without changing the meaning or use of the relation.
true
View integration is the process of merging relations together.
true
