Final Chapter #7
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
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
All of the following are new data types added in SQL:200n EXCEPT: A) BIGINT. B) BIT. C) MULTISET. D) XML.
B
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
All of the following are part of the coding structure for triggers EXCEPT: A) event. B) condition. C) selection. D) action.
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
RANK and DENSE-RANK are examples of: A) ceilings. B) door functions. C) window functions. D) moving functions.
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
________ differs from array because it can contain duplicates. A) BIGINT B) XML C) MULTISET D) TABLE
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
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
Joining tables or using a subquery may produce the same result.
True
Persistent Stored Modules are extensions defined in SQL:1999 that include the capability to add and drop modules of code.
True
RDBMSs store database definition information in system-created tables which can be considered a data dictionary.
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
The UNION clause is used to combine the output from multiple queries into a single result table.
True
The advantages of SQL-invoked routines are flexibility, efficiency, shareability and applicability.
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
The joining condition of an equi-join is based upon an equality.
True
Triggers have three parts: the event, the condition, and the action.
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
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
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
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
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
________ 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
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 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 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
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
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
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
While triggers run automatically, ________ do not and have to be called. A) trapdoors B) routines C) selects D) updates
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 routine is a named set of SQL statements that are considered when a data modification occurs.
False
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 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
All of the following are advantages of SQL-invoked routines EXCEPT: A) flexibility. B) efficiency. C) sharability. D) security.
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
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 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
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
DBA_USERS contains comments on all tables in an Oracle database.
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
A function has only input parameters but can return multiple values.
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
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
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 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
A correlated subquery is executed once for each iteration through the outer loop.
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 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
An SQL query that implements an outer join will return rows that do not have matching values in common columns
True
Constraints are a special case of triggers.
True
Correlated subqueries are less efficient than queries that do not use nesting.
True
Establishing IF-THEN-ELSE logical processing within an SQL statement can now be accomplished by using the CASE keyword in a statement.
True
Figuring out what attributes you want in your query before you write the query will help with query writing.
True