（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：（D、E）

解析：

B（X）单行函数可以嵌套任意层，而分组函数最多可以嵌套2层。

C（X）也可以是函数的返回值

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Oracle Certificate Profession 1Z0-051-04