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

答案: DE
考点：单行函数

A.单行函数只能接收一个参数，错误，单行函数可以接收一个或多个参数
B.单行函数最多嵌套两层，错误，单行函数可以嵌套多层，多行函数最多嵌套两层
C.参数只能是列值或者常量，错误，参数也可以是变量或者表达式
D.对于查询表中的每一行，单行函数返回一行结果，正确
E.函数返回结果的数据类型可以和引用的数据类型不同，正确

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【OCP】Oracle 11g OCP 1Z0-051 004

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