多选题Which two statements are true regarding the USING and ON clauses in table joins?（）ABoth USING and ON clauses can be used for equijoins and nonequijoinsBAmaximum of one pair of columns can be joined between two tables using the ON clauseCThe ON clause c

第1题：

Which three statements are true regarding subqueries?（）

• A、Subqueries can contain GROUP BY and ORDER BY clauses 
• B、Main query and subquery can get data from different tables 
• C、Main query and subquery must get data from the same tables 
• D、Subqueries can contain ORDER BY but not the GROUP BY clause 
• E、Only one column or expression can be compared between the main query and subquery
• F、 Multiple columns or expressions can be compared between the main query and subquery

第2题：

What is true about joining tables through an equijoin?（）

• A、You can join a maximum of two tables through an equijoin.
• B、You can join a maximum of two columns through an equijoin.
• C、You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
• D、To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
• E、You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

第3题：

Which two are true about aggregate functions? （）

• A、You can use aggregate functions in any clause of a SELECT statement.
• B、You can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.
• C、You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
• D、You can pass column names, expressions, constants, or functions as parameter to an aggregate function.
• E、You can use aggregate functions on a table, only by grouping the whole table as one single group.
• F、You cannot group the rows of a table by more than one column while using aggregate functions.

第4题：

Which two statements are true regarding subqueries? （）

• A、A subquery can retrieve zero or more rows 
• B、Only two subqueries can be placed atone level 
• C、A subquery can be used only in SQL query statements 
• D、A subquery can appear on either side of a comparison operator 
• E、There is no limit on the number of subquery levels in the WHERE clause of a SELECT statement 

第5题：

Which three statements are true regarding single-row functions？（）

• A、 They can accept only one argument.
• B、 They can be nested up to only two levels.
• C、 They can return multiple values of more than one data type.
• D、 They can be used in SELECT， WHERE， and ORDER BY clauses.  
• E、 They can modify the data type of the argument that is referenced.
• F、 They can accept a column name， expression， variable name， or a user-supplied constant as arguments.

第6题：

Which two statements are true regarding the USING and ON clauses in table joins?（）

• A、Both USING and ON clauses can be used for equijoins and nonequijoins 
• B、Amaximum of one pair of columns can be joined between two tables using the ON clause 
• C、The ON clause can be used to join tables on columns that have different names but compatible data types 
• D、The WHERE clause can be used to apply additional conditions in SELECT statements containing the ON or the USING clause 

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第13题：

Which two statements are true about using the isUserInRole method to implement security in a Java EEapplication？（）

• A、It can be invoked only from the doGet or doPost methods.
• B、It can be used independently of the getRemoteUser method.
• C、Can return "true" even when its argument is NOT defined as a valid role name in the deployment descriptor.
• D、Using the isUserInRole method overrides any declarative authentication related to the method in which it is invoked.

第14题：

Which two statements are true about WHERE and HAVING clauses? （）

• A、A WHERE clause can be used to restrict both rows and groups.
• B、A WHERE clause can be used to restrict rows only.
• C、A HAVING clause can be used to restrict both rows and groups.
• D、A HAVING clause can be used to restrict groups only.
• E、A WHERE clause CANNOT be used in a query of the query uses a HAVING clause.
• F、A HAVING clause CANNOT be used in subqueries.

第15题：

Which two statements regarding a SQL profile are true？（）

• A、 It is built by Automatic Tuning Optimizer.
• B、 It cannot be stored persistently in the data dictionary.
• C、 It can be used by the query optimizer automatically.
• D、 It can be created manually by using the CREATE PROFILE command.

第16题：

Which two statements are true about a job chain? （）(Choose two.)

• A、A job chain can contain a nested chain of jobs.
• B、The jobs in a job chain cannot have more than one dependency.
• C、A job of the CHAIN type can be run using event-based or time-based schedules.
• D、The jobs in a job chain can be executed only by using the events generated by the Scheduler

第17题：

Which two statements are true about a job chain？（）

• A、 A job chain can contain a nested chain of jobs
• B、 The jobs in a job chain cannot have more than one dependency
• C、 A job of the CHAIN type can be run using event-based or time-based schedules
• D、 The jobs in a job chain can be executed only by using the events generated by the Scheduler

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