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create table A表
(ID int, NAME varchar(20))
insert into A表
select 1, '王老师' union all
select 2, '李老师' union all
select 3, '赵老师'
create table B表
(NAME varchar(20), GRADER varchar(20))
insert into B表
select '王老师', '三年级一班' union all
select '王老师', '三年级二班' union all
select '王老师', '三年级三班' union all
select '赵老师', '五年级一班' union all
select '赵老师', '五年级二班'
select ID,
NAME,
(select count(1) from B表 b where b.NAME=a.NAME) 'COUNT'
from A表 a
/*
ID NAME COUNT
----------- -------------------- -----------
1 王老师 3
2 李老师 0
3 赵老师 2
(3 row(s) affected)
*/
----------------------------------------------------------------
-- Author :DBA_Huangzj(發糞塗牆)
-- Date :2013-04-18 16:04:43
-- Version:
-- Microsoft SQL Server 2008 R2 (SP1) - 10.50.2500.0 (X64)
-- Jun 17 2011 00:54:03
-- Copyright (c) Microsoft Corporation
-- Enterprise Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1, v.721)
--
----------------------------------------------------------------
--> 测试数据:[A]
if object_id('[A]') is not null drop table [A]
go
create table [A]([ID] int,[NAME] varchar(6))
insert [A]
select 1,'王老师' union all
select 2,'李老师' union all
select 3,'赵老师'
--> 测试数据:[B]
if object_id('[B]') is not null drop table [B]
go
create table [B]([NAME] varchar(6),[GRADER] varchar(10))
insert [B]
select '王老师','三年级一班' union all
select '王老师','三年级二班' union all
select '王老师','三年级三班' union all
select '赵老师','五年级一班' union all
select '赵老师','五年级二班'
--------------开始查询--------------------------
--select * from [B]
--------------开始查询--------------------------
SELECT a.*,ISNULL(b.[count] ,0)[count]
from [A] a LEFT JOIN (SELECT NAME ,count(1) [count] FROM B GROUP BY NAME)b ON a.NAME=b.name
----------------结果----------------------------
/*
ID NAME count
----------- ------ -----------
1 王老师 3
2 李老师 0
3 赵老师 2
*/