请问这样的查询，SQL语句怎么样写会比较好

显示全部楼层 · 2010-3-1 11:07:22

例如：我想取得aabbcc dd 这四个表当中最大的ID号，请问SQL语句怎样写会比较好点？

千问 · 2010-3-1 11:07:22

请问各位高手，这个语句应该怎么写比较好啊

千问 · 2010-3-1 11:07:22

select max(id) from
(select max(id) as id from a),
(select max(id) as id from b),
(select max(id) as id from c),
(select max(id) as id from d)

千问 · 2010-3-1 11:07:22

上面的语句执行不了啊

千问 · 2010-3-1 11:07:22

最初由 rollingpig 发布
[B]select max(id) from (
(select max(id) as id from a) union all
(select max(id) as id from b) union all
(select max(id) as id from c) union all
(select max(id) as id from d)
)
[/B]