OCP-1Z0-051-2015-26题

QUESTION NO: 26

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

A. They can be nested only to two levels

B. They always return a single result row for every row of a queried table

C. Arguments can only be column values or constant

D. They can return a data type value different from the one that is referenced

E. They accept only a single argument
Answer: B,D

Explanation:关于函数解释
A function is a program written to optionally accept input parameters, perform an operation, or return a single value. 

函数可以随意写，接收输入参数，展示表达式，或者返回单个值

A function returns only one value per execution.一个函数每次执行能返回单个值

Three important components form the basis of defining a function. The first is the input parameterlist. 三个重要的关于函数组成部分定义。第一，输入参数列表 

It specifies zero or more arguments that may be passed to a function as input for processing.

These arguments or parameters may be of differing data types, and some are mandatory whileothers may be optional. 返回的数据类型值可以与之前引用的数据类型不同

The second component is the data type of its resultant value. Upon execution, only one value is returned by the function.第二个 每行总是返回一个结果行

 The third encapsulates the details of the processing performed by the function and contains the program code that optionally manipulates

the input parameters, performs calculations and operations, and generates a return value.

A. 只可以被嵌套两级，错误，可以被全套多级

B. 对于查询表的每一行总是返回一个结果行.正确。

C. 参数arguments只能是列值或者常量constant.，参数还可以是变量和表达式

D. 返回的数据类型值可以与之前引用的数据类型不同，正确。

E. 只接受一个参数，错误，可以接受一个或多个参数