斜槓人生

 

--You can use dynamic SQL in informix - see this link for more details.
--https://www.ibm.com/developerworks/data/library/techarticle/dm-0806mottupalli/index.html

DEFINE v_sql VARCHAR(250);

LET v_sql = "select name from employees";

IF IN_PARAMETER = 1 THEN
   LET v_sql = v_sql || " WHERE active = true"
ELSE
   LET v_sql = v_sql || " WHERE idboss = 3"
END IF;

PREPARE stmt FROM v_sql;
EXECUTE stmt;

FREE stmt;

--If you can't use dynamic SQL, the next best thing would be:

IF IN_PARAMETER = 1 THEN
   select name from employees WHERE active = true;
ELSE
   select name from employees WHERE idboss = 3;
END IF;