這段時間在看SAAS方面的書籍時發現一個關于數據處理的問題。里面講到一種擴展性非常好的方法。但一直到今天終于在網上找到了。只可惜現在還在探索,只是找到一個例子而已。我在這里把共享希望對大家有用。下面的語句在sql server 2005中我測試過沒有問題。
1: 列轉為行:
eg1:
Create table test (name char(10),km char(10),cj int)
go
insert test values('張三','語文',80)
insert test values('張三','數學',86)
insert test values('張三','英語',75)
insert test values('李四','語文',78)
insert test values('李四','數學',85)
insert test values('李四','英語',78)
想變成
姓名 語文 數學 英語
張三 80 86 75
李四 78 85 78
declare @sql varchar(8000)
set @sql = 'select name'
select @sql = @sql + ',sum(case km when '''+km+''' then cj end) ['+km+']'
from (select distinct km from test) as a
select @sql = @sql+' from test group by name'
exec(@sql)
drop table test
eg2:
有表A,
id pid
1 1
1 2
1 3
2 1
2 2
3 1
如何化成表B:
id pid
1 1,2,3
2 1,2
3 1
或者是從表B變成A(不要用游標)
以前有相似的列子,現在找不到了,幫幫忙!
--1.創建一個合并的函數
create function fmerg(@id int)
returns varchar(8000)
as
begin
declare @str varchar(8000)
set @str=''
select @str=@str+','+cast(pid as varchar) from 表A where id=@id
set @str=right(@str,len(@str)-1)
return(@str)
End
go
--調用自定義函數得到結果
select distinct id,dbo.fmerg(id) from 表A
2:
/*********** 行轉列 *****************/
測試:
create table t1 (a int,b int,c int,d int,e int,f int,g int,h int)
insert t1 values(15, 9, 1, 0, 1, 2, 2, 0)
declare @ varchar(8000)
set @=''
select @=@+rtrim(name)+' from t1 union all select ' from syscolumns where id=object_id('t1')
set @=left(@,len(@)-len(' from t1 union all select '))
--PRint @
exec('select '+@+' from t1')
a
-----------
15
9
1
0
1
2
2
0
===============================================================================
以下個帶出的問題:
===============================================================================
3.將結果矩陣轉置
if exists (select * from sysobjects where id = object_id('proc_sky_blue') and xtype ='P')
drop proc proc_sky_blue
go
create proc proc_sky_blue (@tablename varchar(200))
as
begin
set nocount on
declare @col nvarchar(256)
declare @makesql nvarchar(4000)
declare @insertsql nvarchar(4000)
declare @caculatesql nvarchar(400)
declare @count int
declare @i int
create table #tmp (colname nvarchar(20))
select @caculatesql = 'select @count=count(1) from ' + @tablename
exec sp_executesql @caculatesql, N'@count int output',@count output
if @count >=1024
begin
raiserror('表的行數太多了,我轉不了',16,1)
end
else
begin
select @i=0
while @count >0
begin
select @i=@i+1
select @makesql = 'alter table #tmp add col'+convert(varchar(20),@i)+' int'
exec(@makesql)
select @count=@count-1
end
declare my_cursor cursor for
select name from syscolumns where id=object_id(@tablename) order by colid
open my_cursor
fetch next from my_cursor into @col
while @@fetch_status = 0
begin
select @makesql ='select @insertsql= @insertsql + convert(varchar(4),'+@col+') +'','' from ' +@tablename
select @insertsql =N'insert #tmp values ('''+@col+ ''','
execute sp_executesql @makesql,N'@insertsql nvarchar(4000) output' ,@insertsql output
select @insertsql = left(@insertsql,len(@insertsql)-1) +')'
exec(@insertsql)
fetch next from my_cursor into @col
end
close my_cursor
deallocate my_cursor
select * from #tmp
set nocount off
end
end
go
----------------分析
declare @tablename varchar(200)
set @tablename='table1'
begin
set nocount on
declare @col nvarchar(256)
declare @makesql nvarchar(4000)
declare @insertsql nvarchar(4000)
declare @caculatesql nvarchar(400)
declare @count int
declare @i int
create table #tmp (colname nvarchar(20))
select @caculatesql = 'select @count=count(1) from ' + @tablename
exec sp_executesql @caculatesql, N'@count int output',@count output
if @count >=1024
begin
raiserror('表的行數太多了,我轉不了',16,1)
end
else
begin
select @i=0
while @count >0
begin
select @i=@i+1
select @makesql = 'alter table #tmp add col'+convert(varchar(20),@i)+' int'
exec(@makesql)
select @count=@count-1
end
declare my_cursor cursor for
select name from syscolumns where id=object_id(@tablename) order by colid
open my_cursor
fetch next from my_cursor into @col
while @@fetch_status = 0
begin
select @makesql ='select @insertsql= @insertsql + convert(varchar(4),'+@col+') +'','' from ' +@tablename
select @insertsql =N'insert #tmp values ('''+@col+ ''','
execute sp_executesql @makesql,N'@insertsql nvarchar(4000) output' ,@insertsql output
select @insertsql = left(@insertsql,len(@insertsql)-1) +')'
select @insertsql
--exec(@insertsql)
fetch next from my_cursor into @col
end
close my_cursor
deallocate my_cursor
select * from #tmp
set nocount off
drop table #tmp
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