mysql的一些积累

1.MySQL 标量子查询

标量子查询是指子查询返回的是单一值的标量，如一个数字或一个字符串，也是子查询中最简单的返回形式。

一个标量子查询的例子如下：

SELECT * FROM article WHERE uid = (SELECT uid FROM user WHERE status=1 ORDER BY uid DESC LIMIT 1)