MIS336 Test #1
In order for a table to be a relation, the following conditions must hold:
1. Each column must have a name. Within one table, each column name must be unique. 2. Within one table, each row must be unique. 3. 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. 4. All values in each column must be from the same domain.
Associative Entity are more flexible compared with M-N relationships in situations when:
1. additional attributes (usually times, dates, quantities and/or amounts) need to be added to the clarify a relationship. 2. other entities need to be related to a relationship; e.g. representing relationships of degree 3 or higher. 3.novice designers are better off using associative entities as it helps with identifying where to put hard to place attributes/relationships.
Each cardinality symbol is compose of two parts:
1. maximum cardinality. 2. minimum cardinality (participation)
A regular entity must have at least one of the following attributes: A) Unique attribute. B) Composite attribute. C) Multivalued attribute. D) Derived attribute.
A.
An Attribute is ( ) is a: A) Composite attribute B) Multivalued attribute C) Derived attribute D) Unique composite attribute
A.
How many entities are depicted by the following requirements?School XYZ keeps track of its 100 students, 10 teachers, and 5 classrooms. A) 3. B) 4. C) 115. D) 116.
A.
How many entities are involved in a unary relationship? A) 1. B) 2. C) More than 2. D) Between 1 and 2.
A.
If a 1:M relationship is optional on both sides, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0. B) 1. C) 2. D) 3.
A.
If a 1:M relationship is optional on both sides, which of the following is true? A) The resulting foreign key can have null (empty) values. B) The resulting foreign key cannot have null (empty) values. C) The resulting foreign key must have null (empty) values. D) No foreign key is created as a result of mapping such a relationship.
A.
If a 1:M relationship is optional on the 1 side and mandatory on the M side, which of the following is true? A) The resulting foreign key can have null (empty) values. B) The resulting foreign key cannot have null (empty) values. C) The resulting foreign key must have null (empty) values. D) No foreign key is created as a result of mapping such a relationship.
A.
If a 1:M relationship is optional on the M side and mandatory on the 1 side, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0. B) 1. C) 2. D) 3.
A.
If an M:N relationship is optional on both sides, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) 0. B) 1. C) 2. D) 3.
A.
Joe is an example of: A) Data. B) Metadata. C) Data Type. D) DBMS.
A.
Maximum cardinality can be: A) One or many. B) Zero or many. C) Optional or mandatory. D) Optional or many.
A.
Which of the following is a possible type of relationship (maximum cardinality-wise)? A) One-to-one. B) Zero-to-zero. C) Zero-to-one. D) Zero-to-many.
A.
Which of the following requires that the end user knows how to issue commands to the specific DBMS? A) Direct interaction. B) Indirect interaction. C) Both direct and indirect interaction. D) Neither direct nor indirect interaction.
A.
A multivalued composite attribute can be used to depict which of the following weak entity concepts? A) Partially unique attribute. B) Identifying relationship. C) A regular (non-identifying) one-to-many relationship between a weak entity and a regular entity. D) A regular (non-identifying) many-to-many relationship between a weak entity and a regular entity.
B.
A relation resulting from a weak entity has a non-composite primary key when the identifying relationship is: A) Optional on both sides. B) 1:1. C) 1:M. D) M:N.
B.
Database implementation involves using ________ to implement the database model as an actual database. A) Front-end applications. B) DBMS. C) Database system. D) Indirect interaction.
B.
FirstName is an example of: A) Data. B) Metadata. C) Data Type. D) DBMS.
B.
Front-end applications facilitate: A) Direct use. B) Indirect use. C) Both direct and indirect use. D) Neither direct nor indirect use.
B.
How many entities are involved in a binary relationship? A) 1. B) 2. C) More than 2. D) Between 1 and 2.
B.
If a 1:M relationship is mandatory on both sides, which of the following is true? A) The resulting foreign key can have null (empty) values. B) The resulting foreign key cannot have null (empty) values. C) The resulting foreign key must have null (empty) values. D) No foreign key is created as a result of mapping such a relationship.
B.
If a 1:M relationship is mandatory on the 1 side and optional on the M side, which of the following is true? A) The resulting foreign key can have null (empty) values. B) The resulting foreign key cannot have null (empty) values. C) The resulting foreign key must have null (empty) values. D) No foreign key is created as a result of mapping such a relationship.
B.
If an entity has three unique attributes, how many primary keys will its mapped relation have? A) 0. B) 1. C) 2. D) 3.
B.
The difference in the scope of databases is reflected in the: A) Number of the development steps. B) Cost in time and resources required for each of the development steps. C) Level of importance of each of the development steps. D) Order of the development steps.
B.
The following attribute represents a collection of attributes: A) Unique attribute. B) Composite attribute. C) Multivalued attribute. D) Derived attribute.
B.
Which of the following is NOT a possible cardinality constraint? A) Optional one. B) Optional zero. C) Optional many. D) Mandatory one.
B.
Which of the following is an example of analytical information? A) Information about the amount of money in a checking account. B) Information showing which airline routes in the United States have the most sales. C) Information about the cost of a product. D) Information showing the destination and origin of a particular airline route in the United States.
B.
Which of the following is typically found in the database metadata? A) Employee names. B) Data types. C) Student ages. D) Product prices.
B.
An associative entity is used as an alternative way of depicting: A) 1:M relationships. B) 1:1 relationships. C) M:N relationships. D) Multivalued attributes.
C.
An entity with two multivalued attributes will be mapped as how many relations? A) 1. B) 2. C) 3. D) 4.
C.
Autonumber data type option: A) Automatically converts the existing data type into a number type. B) Assigns a number to each of the used data types. C) Enables automatic generation of consecutive numeric data values in a column. D) Enables automatic counting of columns in a table.
C.
Column A and Column B are composite primary key Which of the following statements regarding the table below is true? Column A - Column B - Column C A) Every value in Column A is unique. B) Every value in Column B is unique. C) Every combination of values in Column A and Column B within the same row is unique. D) All of the above.
C.
Information can be used for: A) Operational purposes only. B) Analytical purposes only. C) Operational and analytical purposes. D) Neither for operational nor for analytical purposes.
C.
Minimum cardinality can be: A) One or many. B) Zero or many. C) Optional or mandatory. D) Optional or many.
C.
The description of the structure and the properties of the data fits into which category? A) Information. B) Data. C) Metadata. D) DBMS.
C.
The following attribute can contain more than one value for each entity instance. A) Unique attribute. B) Composite attribute. C) Multivalued attribute. D) Derived attribute.
C.
Tuple is a synonym for A) Column. B) Field. C) Row. D) Table.
C.
Which of the following is NOT true? In a relational table: A) Two columns can have the same values. B) All column names are different. C) Two rows can have the same values. D) All values in a column are from the same domain.
C.
Which of the following is a database use action? A) Securing data. B) Storing data. C) Modifying data. D) Modeling data.
C.
Which of the following is a legitimate exact minimum and maximum cardinality? A) (20, 10). B) (5, 0). C) (5, 10). D) (5, 4).
C.
Which of the following is a part of the database requirements step? A) Database deployment. B) Logical modeling. C) Conceptual modeling. D) Database implementation.
C.
Which of the following is an example of a daily operational procedure or task supported by an operational database? A) Deducting the correct amount of money from a customer's checking account upon an ATM withdrawal. B) Issuing a correct bill to a customer who purchased an airline ticket. C) Both A and B. D) None of the above.
C.
________ are in charge of implementing the database model as a functioning database using the DBMS software. A) Database analysts. B) Database architects. C) Database developers. D) DBAs.
C.
An ER diagram that contains two entities involved in two separate M:N relationships will be mapped as how many relations? A) 1. B) 2. C) 3. D) 4.
D.
An M:N relationship that can have multiple occurrences between the same instances of involved entities can be depicted as a: A) Weak entity with one owner. B) Multivalued composite attribute. C) Unary M:N relationship. D) Weak entity with two owners.
D.
DBMS is software used for the following purpose: A) Creation of databases. B) Insertion, storage, retrieval, update, and deletion of the data in the database. C) Maintenance of databases. D) All of the above.
D.
End users can vary in: A) Their level of technical sophistication. B) The amount of data they need. C) The frequency with which they access the database system. D) All of the above.
D.
If a 1:M relationship is mandatory on both sides, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side CANNOT have less than ________ records. A) 0. B) 1. C) 2. D) 3.
D.
If a 1:M relationship is mandatory on the M side and optional on the 1 side, and if the table resulting from the 1 side has 3 records, then the table resulting from the M side cannot have less than ________ records. A) 0. B) 1. C) 2. D) 3.
D.
If an M:N relationship is mandatory on both sides, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) 0. B) 1. C) 2. D) 3.
D.
If an M:N relationship is mandatory on one side and optional on the other side, and if both relations resulting from the entities involved in the relationship each have 3 records, then the resulting bridge relation cannot have less than ________ records. A) o. B) 1. C) 2. D) 3.
D.
Implicit changes of requirements are permitted during: A) Database deployment. B) Logical modeling. C) Database use. D) Implicit changes of requirements are not permitted .
D.
Relation is a synonym for A) Column. B) Field. C) Row. D) Table.
D.
Relationship attributes may be necessary in a relationship of what type? A) One-to-one. B) One-to-many. C) Zero-to-many. D) Many-to-many.
D.
Requirements can be refined and/or expanded following: A) Database deployment. B) Logical modeling. C) Database use. D) All of the above.
D.
The values of the following attribute are NOT permanently stored in a database. A) Unique attribute. B) Composite attribute. C) Multivalued attribute. D) Derived attribute.
D.
Which of the following is NOT true? In a relational database: A) Two tables can be a part of the same database. B) Two tables can have the same number of columns. C) Two tables can have the same number of rows. D) Two tables can have the same names.
D.
Which of the following is NOT true? Mapping an M:N relationship that has no attributes will result in: A) A new relation. B) Two foreign keys. C) A composite primary key. D) A foreign key in both of the relations mapped from the involved entities.
D.
Which of the following is a component of a database system? A) Database. B) DBMS. C) Front-end applications. D) All of the above.
D.
Which of the following is a format in which data can appear? A) Text. B) Numbers. C) Image. D) All of the above.
D.
Primary Key
Every relation has a column(or a set of column in some cases) that serves as a primary key. The purpose of the primary key is to distinguish one row from another in a relation. Each relation must have a primary key, which is a column(or a set of columns) whose value is unique for each row.
T or F: A foreign key column must have the same name as the primary key column it refers to.
FALSE
T or F: Exact maximum cardinality is calculated by adding the exact minimum cardinalities.
FALSE
T or F: If one of two identical relational tables has the last column row moved to the first place, those tables are no longer identical.
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 and 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.
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.
Associative (or Linking) Entities
Replaces M-N relationship with a weak entity between two 1-M identifying relationships; the resulting weak entity is call an associative entity and often has independent meaning
T or F: A restriction specifying that no salary entered into the salary column can be higher than $300,000 is an example of a business rule.
TRUE
T or F: A unary relationship can have one or many maximum cardinalities on either side.
TRUE
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
Foreign key
a column in a relation that refers to a primary key column in another (referred) relation
Entity-relationship(ER) Modeling
a technique that enables the structuring and organizing of the requirements collection process and provides a way to graphically represent the requirements.
Information that is collected in database systems can be used for two purposes:
an operation purpose and an analytical purpose.
Entities
are constructs that represent what the database keeps track of
synonyms for column
attribute. field.
Degree of a relationship indicates how many entities are involved in a relationship
binary involves two entities. Unary (Recursive) occurs when an entity is involved in a relationship with itself
Attributes
describes a characteristic of an entity
relationships
each entity must be related to at least one other entity via a construct called a realtionship
Weak Entity
is a construct in a ER diagram used to depict entities that do not have a unique attribute of their own. Within an ER diagram, each weak entity must be associated with its owner entity via an identifying relationship
Database Management System (DBMS)
is a software used for the following purposes. 1. creation of databases. 2. insertion, storage, retrieval, update, and deletion of the data in the database. 3. maintenance of databases.
Database
is structured collection of related data stored on a computer medium.
Metadata
is the data that describes the structure and the properties of the data. is essential for the proper understanding and use of the data.
How are cardinality constraints marked
on an ER diagram as symbols placed next to an entity rectangle on the line connecting the entity rectangle to the relationship diamond.
Relational DBMS
oracle, MySQL, Microsoft SQL server, PostgressSQL, IBM DB2, Teradata
Data
refers to facts that are recorded and can be accessed
Information
refers to the data that is accessed by a user for some particular putpose
Analytical information
refers to the information collected and used in support of analytical tasks. Example. Information showing a pattern of use of ATM machines
Operational information (transactional information)
refers to the information collected and used in support of the day-to-day operational needs in businesses and other organization
synonyms for relation
relational table. table.
Cardinality Constraints
the lines connecting the relationship to the entities include symbols depicting how many instances of one entity can be associated with instances of another entity.
Maximum Cardinality
the part of the cardinality constraint symbol closer to the entity rectangle. Can either be one represented by a the straight bar or represented by the crow's foot symbol -->.
Minimum Cardinality (participation)
the part of the cardinality constraint symbol farther away from the entity rectangle. Can either be optional represented by a circular symbol 0 or mandatory represented by a straight bar.
synonyms for row
turple. record.
