Question

SQL语句查询多个表 通过一个ID

比如 表1
字段是 id name number
12 ‘name’ 123
21 ‘name1’ 321
表2 是
字段 id arg istrue
12 2 1
32 2 0
通过ID = 12
同时对这两个表查找？

Answer 1

select * from 表1 where id = 12
union all
select * from 表2 where id = 12

如果arg是数值型的则要用cast或convert转换成字符

Answer 2

select * from t1 as a inner join t2 as b on a.id=b.id
where a.id=12

Answer 3

select * from
(select * from 表1
union
select * from 表2)
where id = 12

Answer 4

select * from 表1，表2 where 表1.id = 表2.id and 表1.id = 12;