相关疑难解决方法(0)

为什么这个查询

DELETE FROM test 
WHERE id = ( SELECT id 
             FROM (SELECT * FROM test) temp 
             ORDER BY RAND() 
             LIMIT 1
           );

有时删除 1 行，有时删除 2 行，有时什么都不删除？

如果我用这种形式写：

SET @var = ( SELECT id 
             FROM (SELECT * FROM test) temp 
             ORDER BY RAND() 
             LIMIT 1
           ); 
DELETE FROM test 
WHERE id=@var;

那么它可以正常工作 - 子查询有问题吗？