select a.*,textname=isnull(b.textname,'无') from 表A a left join 表B b on a.id=b.id
select A.*,isnull(B.textname,'无') from A left join B on A.id=B.id
create table A (id int,name varchar(20)) create table B (id int,textname varchar(20)) go insert into A select 1 , 'aa' union select 2, 'bb' union select 3, 'cc'insert into B select 1 , 'aa1' union select 3, 'aa2' ----查询 select A.*,isnull(B.textname,'无') as textname from A left join B on A.id=B.id ---结果id name textname ----------- -------------------- -------------------- 1 aa aa1 2 bb 无 3 cc aa2(所影响的行数为 3 行)
from 表A a left join 表B b on a.id=b.id
from A left join B on A.id=B.id
create table B (id int,textname varchar(20))
go
insert into A
select 1 , 'aa'
union select 2, 'bb'
union select 3, 'cc'insert into B
select 1 , 'aa1'
union select 3, 'aa2'
----查询
select A.*,isnull(B.textname,'无') as textname
from A left join B on A.id=B.id
---结果id name textname
----------- -------------------- --------------------
1 aa aa1
2 bb 无
3 cc aa2(所影响的行数为 3 行)