MySql中游标使用总是多循环一次的解决方法_MySQL

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 doneEND 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。