oracle sql if condition then select statement1 else select statement2

oracle sql if condition then select statement1 else select statement2(oracle sql if condition then select statement1 else select statement2)

问题描述

我有参数 :prmtr，我想要的是使用基于参数输入的选择语句.

I have parameter :prmtr and what I wanted is to use a select statement based on the parameter input.

我试过了:

if :prmtr= 'A' then
    select * from tblA;
else
    select * from tblB;
end if;

但这行不通.

还有其他方法可以做到这一点吗?

Is there some other way to do this?

推荐答案

您可以使用 CURSOR 变量和 PRINT 命令尝试类似的操作.当作为脚本运行时，这适用于 SQL* plus 和 SQL Developer 或 TOAD.

You may try something like this with a CURSOR variable and PRINT command. This works in SQL* plus and in SQL developer or TOAD when run as script.

VARIABLE prmtr VARCHAR2
EXEC :PRMTR := 'A'  -- SET values of parameter

VARIABLE x refcursor -- a cursor variable

DECLARE
BEGIN
    IF :PRMTR = 'A' THEN
      OPEN :x FOR
        SELECT *
        FROM   employees;
    ELSE
      OPEN :x FOR
        SELECT *
        FROM   departments;
    END IF;
END;
/

PRINT x  -- gives you the result of the query.

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