多选题Which three statements are true regarding single-row functions？（）AThey can accept only one argument.BThey can be nested up to only two levels.CThey can return multiple values of more than one data type.DThey can be used in SELECT， WHERE， and ORDER BY c

第1题：

Which two statements about subqueries are true? （）

• A、A subquery should retrieve only one row.
• B、A subquery can retrieve zero or more rows.
• C、A subquery can be used only in SQL query statements.
• D、Subqueries CANNOT be nested by more than two levels.
• E、A subquery CANNOT be used in an SQL query statement that uses group functions.
• F、When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

第2题：

Which three statements about subqueries are true?（）

• A、A single row subquery can retrieve only one column and one row.
• B、A single row subquery can retrieve only one row but many columns.
• C、A multiple row subquery can retrieve multiple rows and multiple columns.
• D、A multiple row subquery can be compared by using the ">" operator.
• E、A single row subquery can use the IN operator.
• F、A multiple row subquery can use the "=" operator.

第3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4题：

Which two statements are true about simple views？（）

• A、Views can be created as read only.
• B、Views are data segments like tables.
• C、Views can be created on the basis of more than one table.
• D、Data manipulation language （DML） operations cannot be performed on views.

第5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

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 

第7题：

Which four are attributes of single row functions? （）

• A、cannot be nested
• B、manipulate data items
• C、act on each row returned
• D、return one result per row
• E、accept only one argument and return only one value
• F、accept arguments which can be a column or an expression

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第13题：

Which three statements about subqueries are true? （）

• A、A main query can have more than one subquery.
• B、A subquery can have more than one main query.
• C、The subquery and main query must retrieve data from the same table.
• D、The subquery and main query can retrieve data from different tables.
• E、Only one column or expression can be compared between the subquery and main query.
• F、Multiple columns or expression can be compared between the subquery and main query.

第14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15题：

Which two statements about subqueries are true?（）

• A、A single row subquery can retrieve data from only one table.
• B、A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.
• C、A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause.
• D、A single row subquery can retrieve data from more than one table.
• E、A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.
• F、A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.

第16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17题：

Which three statements are true regarding the data types in Oracle Database 10g/11g?（）

• A、Only one LONG column can be used per table 
• B、A TIMESTAMP data type column stores only time values with fractional seconds 
• C、The BLOB data type column is used to store binary data in an operating system file 
• D、The minimum column width that can be specified for a VARCHAR2 data type column is one 
• E、The value for a CHAR data type column is blank-padded to the maximum defined column width

第18题：

Which two statements are true regarding listeners（）

• A、Listeners use only the TCP/IP protocol.
• B、Multiple listener processes can run simultaneously on a host.
• C、Multiple database instances can be registered with a single listener.
• D、The listener-related errors can be traced only at the administrative level.
• E、Only one database instance can be registered with a single listener at any time.

第19题：

Which two statements are true regarding single row functions?（）

• A、They accept only a single argument 
• B、They can be nested only to two levels 
• C、Arguments can only be column values or constants 
• D、They always return a single result row for every row of a queried table 
• E、They can return a data type value different from the one that is referenced

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