我们已经使用 phpmyadmin 5.0 从 Mariadb 10.1.21 迁移到 mysql 5.6。 迁移后，我们面临存储过程中的问题

Question

The stored procedure was working fine in Mariadb. After migrating to mysql it is not returning any rows nor any errors. Kindly help to resolve this.

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DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `ONROLL`(IN `SCH_ID` INT, IN `YR_ID` INT)
    MODIFIES SQL DATA
BEGIN
DECLARE GRD_ID INT;
DECLARE FINISHED INT;
DECLARE GRD_CUR CURSOR FOR SELECT DISTINCT GRADE_ID FROM SECTION WHERE SCHOOL_ID = SCH_ID ORDER BY GRADE_ID ASC;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET FINISHED = 0;

CREATE TEMPORARY TABLE ROLL(
GRD_ID INT,
COUNT INT);

OPEN GRD_CUR;
LOOPROWS:LOOP

FETCH GRD_CUR INTO GRD_ID;

IF FINISHED = 0 THEN
    LEAVE LOOPROWS;
END IF;

INSERT INTO ROLL (GRD_ID,COUNT)
SELECT GRD_ID,COUNT(U.ID) FROM USER U JOIN USER_CURRICULUM UC ON UC.USER_ID=U.ID JOIN COHORTS_STUDENTS CS ON CS.STUDENTS_ID=UC.USER_ID AND CS.ACADEMIC_YEAR=UC.YEAR_ID JOIN COHORTS C ON C.ID = CS.COHORTS_ID WHERE UC.SCHOOL_ID=SCH_ID AND UC.GRADE_ID=GRD_ID AND UC.YEAR_ID=YR_ID;

END LOOP;
    CLOSE GRD_CUR;
    SELECT * FROM ROLL;
    DROP TABLE ROLL;
END$$
DELIMITER ;

Answer 1

Your procedure code does not assign an initial value to FINISHED , you just declare it as INT , and set it to zero in your NOT FOUND handler.

So it is not really determined what value FINISHED has to begin with, and depending on whether it is initialized as zero or a non-zero value by default your FETCH LOOP may terminate early without storing anything in your ROLL table.

By changing the FINISHED declaration to

DECLARE FINISHED INT DEFAULT 1;

your could should become deterministic and return the same result on both MariaDB and MySQL.