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create database student
go
use student
create table Member
(
MID char(10) primary key ,
Mname char(50)
)
go
create table F
(
FID char(10) primary key ,
FName char(50)
)
go
create table score
(
SID int primary key identity(1,1),
FID char(10) references F,
MID char(10) references Member,
Score int
)
go
insert into Member values('001','张萨')
insert into Member values('002','王强')
insert into Member values('003','李三')
insert into Member values('004','李四')
insert into F values('001','语文')
insert into F values('002','数学')
insert into F values('003','英语')
insert into F values('004','历史')
insert into score values('001','001',78)
insert into score values('001','002',89)
insert into score values('001','003',70)
insert into score values('001','004',80)
insert into score values('002','001',67)
insert into score values('002','002',67)
insert into score values('002','003',87)
insert into score values('004','001',76)
insert into score values('004','002',96)
insert into score values('004','003',56)
go
select * from Member
select * from f
select * from score
go
select m.MID,Mname,fname
from member m
inner join score s
on s.mid=m.mid
inner join f
on f.fid=s.fid
where m.mid not in (select mid from score group by MID)
select a.* ,stuff((select ','+b.课程 from 表二 b where b.学号=a.学号 for xml path('')),1,1,'')
from 表一 a
1.查询所有考试都没有参加的学生名单,要求显示姓名,学号,科目
SQL code
select m.MID,Mname,fname from member m inner join score s on s.mid=m.mid inner join f on f.fid=s.fid where m.mid not in (select mid from score group by MID)
--沒有選課
SELECT
m.MID,m.Mname,f.FName
FROM Member AS m
CROSS JOIN F
WHERE NOT EXISTS(SELECT 1 FROM score WHERE Mid=m.MID)
--沒有選的課
SELECT
m.MID,m.Mname,f.FName
FROM Member AS m
CROSS JOIN F
LEFT JOIN score AS s ON f.FID=f.FID AND m.MID=s.MID
WHERE s.MID IS NULL
--學生選的課
SELECT
m.MID,m.Mname,STUFF((SELECT ','+F.FName FROM F ,score AS s WHERE s.FID=f.FID AND m.MID=s.MID FOR XML PATH('')),1,1,'') AS FName
FROM Member AS m
1.查询所有考试都没有参加的学生名单,要求显示姓名,学号,科目
改改
;WITH C
AS
(
select a.*,c.FName
from Member AS a
INNER JOIN score AS b ON a.MID=a.MID
INNER JOIN F AS c ON c.FID=b.FID
)
select
a.Mname,FName=stuff(b.FName.value('/R[1]','nvarchar(max)'),1,1,'')
from
(select distinct Mname from C) a
Cross apply
(select FName=(select N','+RTRIM(FName) from C where Mname=a.Mname For XML PATH(''), ROOT('R'), TYPE))b
;WITH C
AS
(
select a.*,c.FName
from Member AS a
INNER JOIN score AS b ON a.MID=a.MID
INNER JOIN F AS c ON c.FID=b.FID
)
select
a.Mname,FName=stuff(b.FName.value('/R[1]','nvarchar(max)'),1,1,'')
from
(select distinct Mname from C) a
Cross apply
(select FName=(select N'+'+RTRIM(FName) from C where Mname=a.Mname For XML PATH(''), ROOT('R'), TYPE))b
select
m.MID,Mname,fname
from
member m
inner join score s
on
s.mid=m.mid
inner join
f
on
f.fid=s.fid
where not exist (select 1 from score where mid=m.mid)
合并列值
--*******************************************************************************************
表结构,数据如下:
id value
----- ------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
需要得到结果:
id values
------ -----------
1 aa,bb
2 aaa,bbb,ccc
即:group by id, 求 value 的和(字符串相加)
1. 旧的解决方法(在sql server 2000中只能用函数解决。)
--=============================================================================
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
--1. 创建处理函数
CREATE FUNCTION dbo.f_strUnite(@id int)
RETURNS varchar(8000)
AS
BEGIN
DECLARE @str varchar(8000)
SET @str = ''
SELECT @str = @str + ',' + value FROM tb WHERE id=@id
RETURN STUFF(@str, 1, 1, '')
END
GO
-- 调用函数
SELECt id, value = dbo.f_strUnite(id) FROM tb GROUP BY id
drop table tb
drop function dbo.f_strUnite
go
/*
id value
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
(所影响的行数为 2 行)
*/
--===================================================================================
2. 新的解决方法(在sql server 2005中用OUTER APPLY等解决。)
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
-- 查询处理
SELECT * FROM(SELECT DISTINCT id FROM tb)A OUTER APPLY(
SELECT [values]= STUFF(REPLACE(REPLACE(
(
SELECT value FROM tb N
WHERE id = A.id
FOR XML AUTO
), ' <N value="', ','), '"/>', ''), 1, 1, '')
)N
drop table tb
/*
id values
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
(2 行受影响)
*/
--SQL2005中的方法2
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
select id, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '')
from tb
group by id
/*
id values
----------- --------------------
1 aa,bb
2 aaa,bbb,ccc
(2 row(s) affected)
*/
drop table tb
/******************************************************************************************************************************************************
合并分拆表数据
整理人:中国风(Roy)
日期:2008.06.06
******************************************************************************************************************************************************/
--> --> (Roy)生成測試數據
if not object_id('Tab') is null
drop table Tab
Go
Create table Tab([Col1] int,[Col2] nvarchar(1))
Insert Tab
select 1,N'a' union all
select 1,N'b' union all
select 1,N'c' union all
select 2,N'd' union all
select 2,N'e' union all
select 3,N'f'
Go
合并表:
SQL2000用函数:
go
if object_id('F_Str') is not null
drop function F_Str
go
create function F_Str(@Col1 int)
returns nvarchar(100)
as
begin
declare @S nvarchar(100)
select @S=isnull(@S+',','')+Col2 from Tab where Col1=@Col1
return @S
end
go
Select distinct Col1,Col2=dbo.F_Str(Col1) from Tab
go
SQL2005用XML:
方法1:
select
a.Col1,Col2=stuff(b.Col2.value('/R[1]','nvarchar(max)'),1,1,'')
from
(select distinct COl1 from Tab) a
Cross apply
(select COl2=(select N','+Col2 from Tab where Col1=a.COl1 For XML PATH(''), ROOT('R'), TYPE))b
方法2:
select
a.Col1,COl2=replace(b.Col2.value('/Tab[1]','nvarchar(max)'),char(44)+char(32),char(44))
from
(select distinct COl1 from Tab) a
cross apply
(select Col2=(select COl2 from Tab where COl1=a.COl1 FOR XML AUTO, TYPE)
.query(' <Tab>
{for $i in /Tab[position() <last()]/@COl2 return concat(string($i),",")}
{concat("",string(/Tab[last()]/@COl2))}
</Tab>')
)b
SQL05用CTE:
;with roy as(select Col1,Col2,row=row_number()over(partition by COl1 order by COl1) from Tab)
,Roy2 as
(select COl1,cast(COl2 as nvarchar(100))COl2,row from Roy where row=1
union all
select a.Col1,cast(b.COl2+','+a.COl2 as nvarchar(100)),a.row from Roy a join Roy2 b on a.COl1=b.COl1 and a.row=b.row+1)
select Col1,Col2 from Roy2 a where row=(select max(row) from roy where Col1=a.COl1) order by Col1 option (MAXRECURSION 0)
生成结果:
/*
Col1 COl2
----------- ------------
1 a,b,c
2 d,e
3 f
(3 行受影响)
*/
--
select a.* ,stuff((select ','+b.课程 from 表二 b where b.学号=a.学号 for xml path('')),1,1,'')
from 表一 a
这个你都嫌复杂?