求大佬解释下这两个SQL语句？

Question

select id from app where id in (select id from app limit 1);
select id from app where id in (select id from (select id from app limit 1) as t);

第一个报错：

select id from app where id in (select id from app limit 1)
1235 - This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'

第二个正确.

Answer 1

MySQL 就规定了 IN/ALL/ANY/SOME 子查询中不能使用 LIMIT 啊

Answer 2

IN/ALL/ANY/SOME 子查询中不能使用 LIMIT

Answer 3

其实第二个是多嵌套了一层以避免这个报错，就是mysql不支持limit和in同时出现在子查询中。
更简单的方法是把子查询放到from后面。
select id from (select id from app limit 1) subqueryname;