Oracle PL/SQL之IN OUT NOCOPY__parameter_the_OUT_NUMBER_parameters_

当前位置: 数据库>oracle

Oracle PL/SQL之IN OUT NOCOPY

来源: 互联网发布时间：2017-04-07

本文导语: Suppose a subprogram declares an IN parameter, an OUT parameter, and an IN OUT parameter. When you call the subprogram, the IN parameter is passed by reference. That is, a pointer to the IN actual parameter is passed to the corresponding formal parameter. So, both parameters reference the same memo...

Suppose a subprogram declares an IN parameter, an OUT parameter, and an IN OUT parameter. When you call the subprogram, the IN parameter is passed by reference. That is, a pointer to the IN actual parameter is passed to the corresponding formal parameter. So, both parameters reference the same memory location, which holds the value of the actual parameter.

By default, the OUT and IN OUT parameters are passed by value. That is, the value of the IN OUT actual parameter is copied into the corresponding formal parameter. Then, if the subprogram exits normally, the values assigned to the OUT and IN OUT formal parameters are copied into the corresponding actual parameters .

相关阅读：Oracle PL/SQL之自定义函数的读一致性

当我们声明一个参数是IN类型时，进行传参是将传给该参数一个实参的指针；

当我们声明一个参数是OUT或者IN OUT类型时，进行传参是将传给该参数一个实参的拷贝；

将NOCOPY应用在传递数据量很大的参数（such as collections, records, and instances of object types）时，可起到优化性能的作用。

当参数是OUT或者IN OUT类型时：没有NOCOPY＝按值传递（ByVal）；加上NOCOPY＝按引用传递（ByRef）。

Test Code:

DECLARE

l_1 NUMBER := 10;

l_2 NUMBER := 20;

l_3 NUMBER := 30;

PROCEDURE test_out

(

p1 IN NUMBER

,x1 IN OUT NUMBER

,x2 IN OUT NOCOPY NUMBER

) IS

BEGIN

x1 := p1;

dbms_output.put_line('inside test_out, x1=' || x1);

您可能感兴趣的文章:

Oracle 子程序参数模式,IN,OUT,NOCOPY

本站(WWW.)旨在分享和传播互联网科技相关的资讯和技术，将尽最大努力为读者提供更好的信息聚合和浏览方式。
本站(WWW.)站内文章除注明原创外，均为转载、整理或搜集自网络。欢迎任何形式的转载，转载请注明出处。