oracle sql if condition then select statement1 else select statement2

问题

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

I tried this:

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

But it wont work.

Is there some other way to do this?

回答1:

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.

来源：https://stackoverflow.com/questions/49787518/oracle-sql-if-condition-then-select-statement1-else-select-statement2