SQL語句 自連表查詢。inner join用法，partition by ，列轉行查詢

use mydb1
go
-- 表T_Employee2
-- Id  Name  Position  Dept
-- 1   張三   員工     市場部
-- 2   李四   經理     銷售部
-- 3   王五   經理     市場部
-- 4   馬六   員工     銷售部
-- 5   錢七   員工     市場部
select * from T_Employee2

-- 需求：查詢表中所有員工以及所在部門的經理姓名。（使用表自連接查詢）

-- 分析：要求返回結果
-- Name  Position  Dept  經理
-- 張三  員工    市場部  王五
-- 馬六  員工    銷售部  李四
-- 錢七  員工    市場部  王五

-- 1、查出 每個部門對應的經理姓名
select Dept,Name from T_Employee2 where Position='經理'
-- 結果：
-- Dept    Name
-- 銷售部  李四
-- 市場部  王五

-- 2、查出 所有的員工
select * from T_Employee2 where Position='員工'
-- 結果：
-- Id  Name  Position  Dept
-- 1   張三   員工     市場部
-- 4   馬六   員工     銷售部
-- 5   錢七   員工     市場部

--3、上面2個表連接查詢，把1個表當做2個表來查詢。
select t1.Name,Position,t1.Dept,t2.Name '經理' from 
(select * from T_Employee2 where Position='員工') as t1
inner join (select Dept,Name from T_Employee2 where Position='經理')as t2 on t1.Dept = t2.Dept

--4、簡化后結果
select t1.Name,Position,t1.Dept,t2.Name '經理' from T_Employee2
as t1
inner join (select Dept,Name from T_Employee2 where Position='經理')as t2 on t1.Dept = t2.Dept
where t1.Position='員工'

-- 結果：
-- Name  Position  Dept  經理
-- 張三  員工    市場部  王五
-- 馬六  員工    銷售部  李四
-- 錢七  員工    市場部  王五

 

 

 

記錄開窗函數分組查詢

--自連表查詢
select t.A,t.B,t.C,t.D from T_D as t
inner join (select B,row_number() over(order by MIN(A)) as E from T_D group by B) tt on t.B=tt.B
order by tt.E

select * from T_D order by min(A) over(partition by B)

 

 

下面是列轉行

go
if OBJECT_ID('tempdb..#temp') is not null
drop table #temp
create table #temp(fnum int, fa int, fb int)
insert into #temp values
(15070, 1, 3),
(15070, 2, 0),
(15070, 3, 3),
(15070, 4, 1),
(15070, 5, 0),
(15070, 7, 1),
(15070, 8, 1),
(15070, 9, 1),
(15070, 10, 0),

(15071, 1, 3),
(15071, 2, 0),
(15071, 3, 1),
(15071, 4, 3),
(15071, 5, 0),
(15071, 7, 3),
(15071, 8, 1),
(15071, 9, 3),
(15071, 10, 3),

(15072, 1, 3),
(15072, 2, 3),
(15072, 3, 0),
(15072, 4, 1),
(15072, 5, 0), 
(15072, 7, 1),
(15072, 8, 0),
(15072, 9, 0),
(15072, 10, 0)
go
--select * from #temp 
--請求轉化成：
--fnum       1  2  3  4  5  7  8  9 10
--15070 3   0   3  1  0 1  1  1   0
--15071    3   0   1  3  0 3  1   3  3
--15072    3   3   0  1  0  1 0   0  0 

select * from (select distinct fnum from #temp) as A
OUTER APPLY 
(select [fbs]= replace(replace(
  (select fb as value FROM #temp as B 
    where fnum = A.fnum order by B.fa FOR XML AUTO
  ),'<B value="',''),'"/>',' ')
)B


--創建新表
go
if OBJECT_ID('tempdb..#new') is not null
drop table #new
create table #new(fnum int,l_1 int,l_2 int,l_3 int,l_4 int,l_5 int,l_7 int,l_8 int,l_9 int,l_10 int)

--循環導入數據
declare @i int = 1;
declare @count int = (select count(*) from (select distinct fnum from #temp) as a);
declare @fnum varchar(50),@fbs varchar(50),@sql varchar(100);

while @i<=@count
begin

select @fnum=fnum, @fbs=fbs from
(select fnum,fbs,ROW_NUMBER() over(order by fnum) as row from (select distinct fnum from #temp) as A
OUTER APPLY 
(select [fbs]= replace(replace(
  (select fb as value FROM #temp as B 
    where fnum = A.fnum order by B.fa FOR XML AUTO
  ),'<B value="',''),'"/>',' ')
)B)tmp
where tmp.row = @i;

 set @sql='insert into #new values('+@fnum+',';
 set @sql=@sql + replace(@fbs,' ',',')+')';
 set @sql=replace(@sql,',)',')');
 exec (@sql) --執行SQL
 --PRINT @sql

set @i=@i+1
end

go

select * from #new

select fnum,
max(case fa when 1 then fb end) F1, 
max(case fa when 2 then fb end) F2,
max(case fa when 3 then fb end) F3,
max(case fa when 4 then fb end) F4,
max(case fa when 5 then fb end) F5,
max(case fa when 7 then fb end) F7,
max(case fa when 8 then fb end) F8,
max(case fa when 9 then fb end) F9,
max(case fa when 10 then fb end) F10 
from #temp group by fnum