好吧,这可能很荒谬,但我已经挠头好几分钟了。这个语法有什么问题?
SET @maxIterations = 10;
SET @i = 0;
myloop: LOOP
SET @i = @i + 1;
UPDATE `mytable`
SET `field` = 'value';
if @i < @maxIterations THEN ITERATE myloop; END IF;
LEAVE myloop;
END LOOP myloop;
我在第 1 行出现错误 near 'myloop: LOOP SET i = i + 1'
最佳答案
您的语法通常是正确的,除了 MySQL 不允许在存储过程或函数(“存储程序”)以外的任何内容中使用流控制结构,如 IF/ELSE、WHILE、LOOP
。此限制is documented here :
MySQL supports the IF, CASE, ITERATE, LEAVE LOOP, WHILE, and REPEAT constructs for flow control within stored programs. It also supports RETURN within stored functions.
您将能够正确地将其创建为存储过程,如下所示:
DELIMITER $$
CREATE PROCEDURE myproc()
BEGIN
SET @maxIterations = 10;
SET @i = 0;
myloop: LOOP
SET @i = @i + 1;
UPDATE `mytable`
SET `field` = 'value';
if @i < @maxIterations THEN ITERATE myloop; END IF;
LEAVE myloop;
END LOOP myloop;
END$$
DELIMITER ;
关于mysql - 如何在 mysql 中正确执行 LOOP,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/23618237/