mysql function parameter not work in where condition of select statement

Question

DELIMITER $$
     CREATE DEFINER=`axistms`@`localhost` FUNCTION `CheckDoc`(`orderId` INT) RETURNS int(11)
DETERMINISTIC
BEGIN
     DECLARE lvl int;
     SELECT count(`id`) INTO lvl FROM `com_carrier_portal_upload_documents` WHERE `orderID`= orderId;
     RETURN lvl;
END$$
DELIMITER ;

any order id pass through orderId parameter its doesn't effect on where condition. Always return count of all records.How to fix this?

Answer 1

I'd suggest you to rename stored procedure argument, do something like this -

CREATE DEFINER = `axistms`@`localhost` FUNCTION `CheckDoc` (orderIdParam int)
RETURNS int(11)
DETERMINISTIC
BEGIN
  DECLARE lvl int;
  SELECT
    COUNT(`id`) INTO lvl
  FROM `com_carrier_portal_upload_documents`
  WHERE `orderID` = orderIdParam;
  RETURN lvl;
END

...because WHERE orderID = orderId can be equal to WHERE true.