DELIMITER ;

DROP FUNCTION IF EXISTS multiurldecode;

DELIMITER |

CREATE FUNCTION multiurldecode (s VARCHAR(4096)) RETURNS VARCHAR(4096)
DETERMINISTIC 
CONTAINS SQL 
BEGIN
       DECLARE pr VARCHAR(4096) DEFAULT '';
       IF ISNULL(s) THEN
          RETURN NULL;
       END IF;       
       REPEAT
          SET pr = s;
          SELECT urldecode(s) INTO s;
       UNTIL pr = s END REPEAT;
       RETURN s;
END;

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DELIMITER ;