SQL中游标的使用--遍历数据逐行更…

--------------------------------------例子1
单纯的游标--------------------------------

  create TABLE Table1

    (

       
a varchar(10),

       
b varchar(10),

       
c varchar(10),

       
CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED

       
(

           
a ASC

       
)

    ) ON
[PRIMARY]

    create
TABLE Table2

    (

       
a varchar(10),

       
c varchar(10),

       
CONSTRAINT [PK_Table2] PRIMARY KEY CLUSTERED

       
(

           
a ASC

       
)

    ) ON
[PRIMARY]

    GO

    Insert into
Table1 values('赵','asds',null)

    Insert into
Table1 values('钱','asds','100')

    Insert into
Table1 values('孙','asds','80')

    Insert into
Table1 values('李','asds',null)

    Insert
into Table2 values('赵','90')

    Insert into
Table2 values('钱','100')

    Insert into
Table2 values('孙','80')

    Insert into
Table2 values('李','95')

    GO

--  drop table Table1

--  drop table Table2

select * from Table1

select * from Table2

declare @name varchar(10)

declare @score varchar(10)

set @name=''

set @score=''

declare mycursor cursor for select a from Table2 where c is not
null

open mycursor

fetch next from mycursor into @name

while(@@fetch_status=0)

begin

-----------------------------------------

select @score=c from Table2 where a=@name

update Table1 set c=@score where
a=@name

-----------------------------------------

fetch next from mycursor into @name

end

close mycursor

deallocate mycursor

go

--------------------------------------例子2
存储过程的使用游标------------------------

------------------------------建表----------------------------------

create table #aaa (id varchar(30),name varchar(30),salary
float)

go

insert into #aaa values('111','张三',4000)

insert into #aaa values('222','李四',5000)

insert into #aaa values('333','王五',6000)

drop table #aaa

drop table #bbb

create table #bbb (id varchar(30),AddSalary float)

go

insert into #bbb values('111',2000)

insert into #bbb values('222',2000)

insert into #bbb values('333',2000)

select * from #aaa

select * from #bbb

------------------------------建表end----------------------------------

------------------------------建立存储过程和游标----------------------------------

create proc PK_test

as

declare @id varchar(30)

declare @salary float

declare mycursor cursor for select
id,AddSalary from #bbb

open mycursor

fetch next from mycursor into @id,@salary

while(@@fetch_status=0)

begin 

update #aaa set salary=(salary+@salary) where id=@id

fetch next from mycursor into @id,@salary

end

close mycursor

deallocate mycursor

go

exec PK_test

drop proc PK_test

------------------------------建立存储过程和游标结束----------------------------------

--------------------------------------例子3
在自定义函数里使用游标--------------------------------功能需求:

问题:

 

假设环境如下：

   
表1：     
ID，
NAME，     
QQ，    
PHONE，

表中数据：     
1      
秦云       
10102800 13500000

               
2      
在路上     
10378   
13600000

               
3      
LEO        
10000   
13900000

   
表2：     
ID， NAME，  上机时间，管理员，

表中数据：    
1  
秦云   
2004-1-1  李大伟

              
2  
秦云   
2005-1-1  马化腾

              
3   
在路上  2005-1-1  马化腾

              
4   
秦云   2005-1-1 
李大伟

              
5   在路上
2005-1-1  李大伟

实现目的：从表1中取所有人员列表，从表2中取上机次数和管理员.

            
上机人员名单   
上机次数   管理员（上这几次机的每个管理员都列出来）

              
秦云            
3            
李大伟，马化腾，李大伟

              
在路上          
2           
马化腾，李大伟

              
LEO             
0      

如果不算管理员那一列的话,我是这样写的。

SELECT  表1.NAME AS 姓名, COUNT(表2.ID) AS 上机次数

FROM  表1 LEFT OUTER JOIN

     
表2 ON 表1.NAME = 表2.NAME

GROUP BY 表1.名称

 

create table 表1( --drop table 表1

ID    
int,

NAME   varchar(10),

QQ    
varchar(10),

PHONE  varchar(20)

)

insert into 表1 values(1  
,'秦云'   
,'10102800'    
,'13500000')

insert into 表1 values(2  
,'在路上' 
,'10378'       
,'13600000')

insert into 表1 values(3  
,'LEO'    
,'10000'       
,'13900000')

create table 表2( --drop table 表2

ID       
int,

NAME   
varchar(10) ,

上机时间  datetime,

管理员   
varchar(10)

)

insert into 表2 
values(1,'秦云'   ,cast('2004-1-1'
as datetime),'李大伟')

insert into 表2 
values(2,'秦云'   ,cast('2005-1-1'
as datetime),'马化腾')

insert into 表2  values (3,'在路上'
,cast('2005-1-1' as datetime),'马化腾')

insert into 表2 
values(4,'秦云'   ,cast('2005-1-1'
as datetime),'李大伟')

insert into 表2  values(5,'在路上' ,cast('2005-1-1'
as datetime),'李大伟')

go

select * from 表1

select * from 表2

 

-----------------------------------------------------灵活的函数----------------------------------create
function GetNameStr(@name nvarchar(10))

returns nvarchar(800)

as

begin

    declare
@nameStr nvarchar(800)

    declare
@tempStr nvarchar(800)

    declare
@flag int

    declare
myCur cursor for ( select 管理员 from 表2 where 表2.NAME = @name )

    open
myCur

    fetch
next from myCur into @tempStr

    set @flag
= 0

    while
@@fetch_status = 0

   
begin--while 开始

    if
@flag = 0 --判断，如果是第一次

   begin

    set
@nameStr = @tempStr

   end

   else

   begin   --否则，进行处理

    set
@nameStr = @nameStr + ',' + @tempStr

   end

   set @flag
= @flag + 1  --循环++

   fetch next
from myCur into @tempStr

   
end--while 结束

    close
myCur

   
deallocate myCur

    return
@nameStr

end

--------------------------------------------函数调用------------------------------

select 表2.NAME as 姓名, count(ID) as 上机次数, dbo.GetNameStr(表2.NAME)
as 管理员

from 表2

where 表2.NAME in ( select 表1.NAME from 表1 )

group by 表2.NAME

select * from 表1

select * from 表2

,count(ID)

select 表2.NAME,count(id),管理员 from 表2 where
表2.Name  in ( select NAME from 表1 )

group by 表2.name