报错：Every derived table must have its own alias

报错：Every derived table must have its own alias

翻译：每个派生表都必须有自己的别名

原因：MySQL要求每个派生表都必须有自己的别名，因为你没给它起名

解决：给派生表起名，as tableName

原sql语句

select id, name, date from
(select * from A
union all
select * from B
order by date desc)
group by id;

修改后的sql语句

select id, name, date from
(select * from A
union all
select * from B
order by date desc) as c
group by id;