MySql中游标使用总是多循环一次的解决方法

CREATE DEFINER = 'root'@'%'

PROCEDURE deyestest.procedure2()

BEGIN 

  DECLARE v_id        INT;

  DECLARE v_userName  VARCHAR(155);

  DECLARE v_mobileNum VARCHAR(55);

  DECLARE v_tmp       VARCHAR(1000);

  DECLARE v_info      VARCHAR(2000);

  DECLARE v_info2     VARCHAR(2000);

  DECLARE v_int       INT;



  DECLARE v_json      LONGTEXT;

  DECLARE done        INT DEFAULT 0;





  DECLARE myCursor CURSOR FOR

  SELECT userId

       , userName

       , mobileNum

  FROM

    user_info

  ORDER BY

    userId

  LIMIT

    2, 2;

  DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;



  OPEN myCursor;

  SET v_info = concat('{');

   REPEAT

  

  IF done <> 1 THEN

  FETCH myCursor INTO v_id, v_userName, v_mobileNum;

  SET v_tmp = concat('[', v_id, ',', v_userName, ',', v_mobileNum, ']', ',');

  SET v_info = concat(v_info, v_tmp);

  FETCH myCursor INTO v_id, v_userName, v_mobileNum;

END IF;

UNTIL done

END REPEAT;

  SET v_int = length(v_info);

  SET v_info = left(v_info, v_int - 1);

  

  SET v_info2 = concat(v_info, '}');

  CLOSE myCursor;

END

 

代码如上：

主要就是注意循环条件done的使用，当游标取到最后一个数据的下一个不存在的数据时，done会被值为1，那么就要在repeat中进行done的判断，当done不为1的时候，才执行循环。