mysql stored procedure that calls itself recursively

Question

I have the following table:

id | parent_id | quantity
-------------------------
1  | null      | 5
2  | null      | 3
3  | 2         | 10
4  | 2         | 15         


        

Answer 1

DELIMITER $$
CREATE DEFINER=`arun`@`%` PROCEDURE `recursivesubtree`( in iroot int(100) , in ilevel int(110) , in locid int(101) )
BEGIN
  DECLARE irows,ichildid,iparentid,ichildcount,done INT DEFAULT 0;

  DECLARE cname VARCHAR(64);
  SET irows = ( SELECT COUNT(*) FROM account WHERE parent_id=iroot and location_id=locid );
  IF ilevel = 0 THEN
    DROP TEMPORARY TABLE IF EXISTS _descendants;
    CREATE TEMPORARY TABLE _descendants (
      childID INT, parentID INT, name VARCHAR(64), childcount INT, level INT
  );
  END IF;
  IF irows > 0 THEN
    BEGIN
      DECLARE cur CURSOR FOR
        SELECT
          f.account_id,f.parent_id,f.account_name,
          (SELECT COUNT(*) FROM account WHERE parent_id=t.account_id and location_id=locid ) AS childcount
        FROM account t JOIN account f ON t.account_id=f.account_id
        WHERE t.parent_id=iroot and t.location_id=locid 
        ORDER BY childcount<>0,t.account_id;
      DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
      OPEN cur;
      WHILE NOT done DO
        FETCH cur INTO ichildid,iparentid,cname,ichildcount;
        IF NOT done THEN
          INSERT INTO _descendants VALUES(ichildid,iparentid,cname,ichildcount,ilevel );
          IF ichildcount > 0 THEN
            CALL recursivesubtree( ichildid, ilevel + 1 );
          END IF;
        END IF;
      END WHILE;
      CLOSE cur;
    END;
  END IF;

  IF ilevel = 0 THEN
    -- Show result table headed by name that corresponds to iroot:
    SET cname = (SELECT account_name FROM account WHERE account_id=iroot and location_id=locid );
    SET @sql = CONCAT('SELECT   CONCAT(REPEAT(CHAR(36),2*level),IF(childcount,UPPER(name),name))',
                  ' AS ', CHAR(39),cname,CHAR(39),' FROM _descendants');
    PREPARE stmt FROM @sql;
    EXECUTE stmt;
    DROP PREPARE stmt;
  END IF;
END$$
DELIMITER ;