Question

mysql存储过程游标循环用哪种比较好

Answer 1

如果没有则插入数据，如果有则更新的方法：
insert into `test` values (a,b) ON DUPLICATE KEY UPDATE `a`=c;

[sql] view plain copy
CREATE PROCEDURE `test`.`new_procedure` ()
BEGIN
-- 需要定义接收游标数据的变量
DECLARE a CHAR(16);
-- 游标
DECLARE cur CURSOR FOR SELECT i FROM test.t;
-- 遍历数据结束标志
DECLARE done INT DEFAULT FALSE;
-- 将结束标志绑定到游标
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
-- 打开游标
OPEN cur;

-- 开始循环
read_loop: LOOP
-- 提取游标里的数据，这里只有一个，多个的话也一样；
FETCH cur INTO a;
-- 声明结束的时候
IF done THEN
LEAVE read_loop;
END IF;
-- 这里做你想做的循环的事件

INSERT INTO test.t VALUES (a);

END LOOP;
-- 关闭游标
CLOSE cur;

END

实例2

[sql] view plain copy
BEGIN
DECLARE Done INT DEFAULT 0;

DECLARE CurrentLingQi INT;

DECLARE ShizuName VARCHAR(30);
/* 声明游标 */
DECLARE rs CURSOR FOR SELECT NodeName, LingQi FROM socialrelation;
/* 异常处理 */
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET Done = 1;

/* 打开游标 */
OPEN rs;

/* 逐个取出当前记录LingQi字段的值，需要进行最大值的判断 */
FETCH NEXT FROM rs INTO ShizuName, CurrentLingQi;
/* 遍历数据表 */
REPEAT
IF NOT Done THEN
SET CurrentLingQi = CurrentLingQi + 60;
/* 如果更新后灵气值大于允许的最大值，则就设置为最大值 */
IF CurrentLingQi >= 1800 THEN
UPDATE socialrelation SET LingQi = 1800 WHERE NodeName = ShizuName;
ELSE
/* 否则，正常更新 */
UPDATE socialrelation SET LingQi = LingQi + 60 WHERE NodeName = ShizuName;
END IF;
END IF;

FETCH NEXT FROM rs INTO ShizuName, CurrentLingQi;

UNTIL Done END REPEAT;

/* 关闭游标 */
CLOSE rs;
END