日期:2014-05-17 浏览次数:20451 次
create table TB1
(
ID INT,
name varchar(10)
)
create table TB2
(
id int,
tb1_id int,
name varchar(10)
)
insert into TB1 select 1,'a'
union all select 2 ,'b'
union all select 3,'c'
insert into TB2 select 1,1,'aa'
union all select 2,1,'aaa'
union all select 3,3,'cc'
select TB1.ID,TB1.name,count(TB2.tb1_id)as TB2_count FROM TB1
LEFT JOIN TB2 ON TB1.ID=TB2.tb1_id
group by tb1.ID,tb1.name
/*
ID name TB2_count
1 a 2
2 b 0
3 c 1
*/