PL/SQL 中的参数模式

原文:https://www.geeksforgeeks.org/argument-modes-in-pl-sql/

参数模式基本上用来描述形式参数的行为。子程序中使用了三种参数模式，如下所示

1. 正流行
2. 输出模式
3. 输入输出模式

模式如何与调用环境交互的表示

• IN Mode : It is the default argument mode in subprogram. This mode passes a constant value from the calling environment into the subprogram.

  示例– 以下示例说明了输入模式参数的工作方式–

  sql SQL> CREATE OR REPLACE PROCEDURE PR1(X IN NUMBER, Y IN NUMBER) S NUMBER; BEGIN S:=X+Y; DBMS_OUTPUT.PUT_LINE('SUM IS : '||S); END PR1;

  输出–

  sql Procedure created.

  sql SQL> DECLARE N1 NUMBER:=10; N2 NUMBER:=20; BEGIN PR1(N1, N2); END;

  输出–

  sql SUM IS : 30 PL/SQL procedure successfully completed. SQL>

• OUT Mode : This mode passes a value from the subprogram to the calling environment.

  示例– 以下示例说明了输出模式参数的工作方式–

  sql SQL> CREATE OR REPLACE PROCEDURE PR2(2 OUT NUMBER) AS X NUMBER:=11; Y NUMBER:=22; BEGIN Z:=X+Y; END;

  输出–

  sql Procedure created.

  sql SQL> DECLARE R NUMBER; BEGIN PR2(R); DBMS_OUTPUT.PUT_LINE('RESULT IS: '||R); END;

  输出–

  sql RESULT IS : 33 PL/SQL procedure successfully completed. SQL>

• IN OUT Mode : This mode is a mixture of both IN n=and OUT mode. Just like IN mode it passes a value from the calling environment in subprogram and like a OUT mode it possibly pass different value from the subprogram back to the calling environment using the same parameter.

  示例– 以下示例说明了输出模式参数的工作方式–

  sql SQL> CREATE OR REPLACE PROCEDURE PR3(2 OUT NUMBER) AS A NUMBER:=11; BEGIN B:=A+B; END;

  输出–

  sql Procedure created.

  sql SQL> DECLARE R NUMBER:=22; BEGIN PR3(R); DBMS_OUTPUT.PUT_LINE('RESULT IS: '||R); END;

  输出–

  sql RESULT IS : 33 PL/SQL procedure successfully completed. SQL>

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