首先看一个存储过程，这个存储过程是为了构造数据使用的。当然贴出来的存储过程简化了一些不必要的表结构。

CREATE PROCEDURE modifyRootEntry()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE userId INT;  
  DECLARE userIdIter CURSOR FOR SELECT DISTINCT user_id from entries;
 
  OPEN userIdIter;

  read_loop: LOOP
    FETCH userIdIter INTO userId;   
    IF done THEN
      LEAVE read_loop;
    END IF;
	INSERT INTO entries (id, name, user_id, parent_id) VALUES(0, 'root_parent', userId, 0);
	UPDATE entries SET parent_id=0 where user_id=userId AND name='file_root' AND parent_id is NULL;
  END LOOP;

  CLOSE userIdIter;
END;

CREATE PROCEDURE modifyRootEntry()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE userId INT;  
  DECLARE userIdIter CURSOR FOR SELECT DISTINCT user_id from entries;
 
  START TRANSACTION; // here !
  OPEN userIdIter;
   	
  read_loop: LOOP
    FETCH userIdIter INTO userId;   
    IF done THEN
      LEAVE read_loop;
    END IF;
	INSERT INTO entries (id, name, user_id, parent_id) VALUES(0, 'root_parent', userId, 0);
	UPDATE entries SET parent_id=0 where user_id=userId AND name='file_root' AND parent_id is NULL;
  END LOOP;

  CLOSE userIdIter;
  COMMIT;// here !
END;

UPDATE entries SET parent_id=0 where user_id=userId AND name='file_root' AND parent_id is NULL;

CREATE PROCEDURE modifyRootEntry()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE userId INT;  
  DECLARE userIdIter CURSOR FOR SELECT DISTINCT user_id from entries;
 
  START TRANSACTION; // here !
  OPEN userIdIter;
   	
  read_loop: LOOP
    FETCH userIdIter INTO userId;   
    IF done THEN
      LEAVE read_loop;
    END IF;
	INSERT INTO entries (id, name, user_id, parent_id) VALUES(0, 'root_parent', userId, 0);
	
  END LOOP;
  UPDATE entries SET parent_id=0 where user_id=userId AND name='file_root' AND parent_id is NULL; // here!
  CLOSE userIdIter;
  COMMIT;// here !
END;

 CREATE PROCEDURE pFastCreateNums (cnt INT UNSIGNED)
BEGIN
DECLARE s INT UNSIGNED DEFAULT 1;
TRUNCATE TABLE Nums;
INSERT INTO Nums SELECT s;
WHILE s*2 <= cnt DO
BEGIN
INSERT INTO Nums SELECT a+s FROM Nums;
SET s = s*2;
END;
END WHILE;
END;