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--SQL Server2008 Merge应用实例
/********************************************************************************
*主题：SQL Server2008 Merge应用实例
*说明：本文是个人学习的一些笔记和个人愚见
* 有很多地方你可能觉得有异议，欢迎一起讨论
*作者：Stephenzhou(阿蒙)
*日期: 2012.12.5
*Mail:szstephenzhou@163.com
*另外：转载请著名出处。
**********************************************************************************/
先不解释 看实例吧
有两个表如下
if OBJECT_ID('Stock') is not null
drop table Stock
go
create table Stock (Symbol varchar(10) primary key,Qty int check(Qty>0))
if OBJECT_ID('Trade') is not null
drop table Trade
go
create table Trade (Symbol varchar(10) primary key,Delta int check(Delta<>0))
--两个表，第一个表Stock为库存表 ，Trade为交易记录表--库存表的记录为：
insert into Stock values('ADVW',10)
insert into Stock values('BYA',5)
--增加三条交易记录，
insert into Trade values('ADVW',5)
insert into Trade values('BYA',-5)
insert into Trade values('NWT',3)
查询两表的内容
select * from Stock
select * from Trade
Symbol Qty
---------- -----------
ADVW 10
BYA 5
(2 行受影响)
Symbol Delta
---------- -----------
ADVW 5
BYA -5
NWT 3
(3 行受影响)
在交易的时候就应该会影响到库存，这时候就用了merge 。等下我们还要用传统方法来处理然后对比下
merge Stock
using Trade
on Stock.Symbol=Trade.Symbol
when matched and (Stock.Qty+Trade.Delta=0) then --就是如果交易和库存一样的话就删除这条记录
DELETE
when matched then
UPDATE SET Stock.Qty+=Trade.Delta --有交易也在库存里有 就减去交易
when not matched then
insert values(Trade.Symbol,Trade.Delta); --有交易没有库存的就加到库存里
select * from Stock
select * from Trade
Symbol Qty
---------- -----------
ADVW 15
NWT 3
(2 行受影响)
Symbol Delta
---------- -----------
ADVW 5
BYA -5
NWT 3
(3 行受影响)
使用Merge进行表复制
生成两个表，在存储过程执行一次复制一次
create table Original(PK int primary key ,Fname varchar(10),Number int)
create table Replica(PK int primary key ,Fname varchar(10),Number int)
create procedure uspSyncReplica
as
Merge Replica r using Original o on o.PK=r.PK
WHEN MATCHED AND (o.Fname!=r.Fname or o.Number!=r.Number) then
update set r.Fname=o.Fname , r.Number=o.Number
when not matched then
insert values(o.PK,o.Fname,o.Number)
when not matched by source then
delete;
INSERT INTO Original VALUES(1,'Stephen',10)
INSERT INTO Original VALUES(2,'Jack',20)
INSERT INTO Original VALUES(3,'BEILL',30)
select *from Original
select *from Replica
/*
PK Fname Number
----------- ---------- -----------
1 Stephen 10
2 Jack 20
3 BEILL 30
(3 行受影响)
PK Fname Number
----------- ---------- -----------
(0 行受影响)
*/
EXECUTE uspSyncReplica
/*
(3 行受影响)
*/
select *from Original
select *from Replica
/*
PK Fname Number
----------- ---------- -----------
1 Stephen 10
2 Jack 20
3 BEILL 30
(3 行受影响)
PK Fname Number
----------- ---------- -----------
1 Stephen 10
2 Jack 20
3 BEILL 30
(3 行受影响)
*/
在上面的存储过程执行一次复制一次 使用$action虚拟列查询MERGE输出如下
alter procedure uspSyncReplica
as
Merge Replica r using Original o on o.PK=r.PK
WHEN MATCHED AND (o.Fname!=r.Fname or o.Number!=r.Number) then
update set r.Fname=o.Fname , r.Number=o.Number
when not matched then
insert values(o.PK,o.Fname,o.Number)
when not matched by source then
delete
output $action ,inserted.*,deleted.*;
INSERT INTO Original VALUES(1,'Stephen',10)
INSERT INTO Original VALUES(2,'Jack',20)
INSERT INTO Original VALUES(3,'BEILL',30)
select *from Original
select *from Replica
EXECUTE uspSyncReplica
$action PK Fname Number PK Fname Number
---------- ----------- ---------- ----------- ----------- ---------- -----------
INSERT 1 Stephen 10 NULL NULL NULL
INSERT 2 Jack 20 NULL NULL NULL
INSERT 3 BEILL 30 NULL NULL NULL
(3 行受影响)
查询复制后的表
PK Fname Number
----------- ---------- -----------
1 Stephen 10
2 Jack 20
3 BEILL 30
(3 行受影响)
PK Fname Number
----------- ---------- -----------
1 Stephen 10
2 Jack 20
3 BEILL 30
(3 行受影响)
如：有一个表 customer， 现在要用一个procedure过程，插入数据，如果表customer中有条数据就更新，没有就新增。
if OBJECT_ID('customer')is not null
drop table customer
go
create table customer(
Customerid int primary key,
Firstname varchar(30),
Lastname varchar(30),
Balance decimal
)
create procedure usUpsertCustomer
(
@Customerid int ,
@Firstname varchar(30),
@Lastname varchar(30),
@Balance decimal
)as
merge customer c
using
(select @Customerid as Customerid ,@Firstname as Firstname ,@Lastname as Lastname ,@Balance as Balance)p
on c.Customerid=p.Customerid
when not matched then
insert values(p.Customerid,p.Firstname,p.Lastname,p.Balance)
when matched then
update set c.Customerid=p.Customerid,c.Firstname=p.Firstname,c.Balance=p.Balance
output $action,deleted.*,inserted.*;
execute usUpsertCustomer 1,'Stephen','Zhou',10
/*
$action Customerid Firstname Lastname Balance Customerid Firstname Lastname Balance
---------- ----------- ------------------------------ ------------------------------ --------------------------------------- ----------- ------------------------------ ------------------------------ ---------------------------------------
UPDATE 1 Stephen Zhou 10 1 Stephen Zhou 10
(1 行受影响)
*/
select * from customer
/*
Customerid Firstname Lastname Balance
----------- ------------------------------ ------------------------------ ---------------------------------------
1 Stephen Zhou 10
(1 行受影响)
*/
execute usUpsertCustomer 1,'Stephen','Jack',20
/*
$action Customerid Firstname Lastname Balance Customerid Firstname Lastname Balance
---------- ----------- ------------------------------ ------------------------------ --------------------------------------- ----------- ------------------------------ ------------------------------ ---------------------------------------
UPDATE 1 Stephen Zhou 10 1 Stephen Zhou 20
(1 行受影响)
*/
select * from customer
/*
Customerid Firstname Lastname Balance
----------- ------------------------------ ------------------------------ ---------------------------------------
1 Stephen Zhou 20
(1 行受影响)
*/
以上基本上介绍了下merge的使用 现在把这个联合 output...into...
create table book (
isbn varchar(20) primary key ,
price decimal,
shelf int
)
create table weeklychange(
isbn varchar(20) primary key,
price decimal,
shelf int
)
create table bookhistory(
[Action] nvarchar(10),
newISBN varchar(20),
newprice decimal,
newshelf int,
oldisbn varchar(20),
oldprice decimal,
oldshelf int,
archivedat datetime2
)
create procedure uspupdatebooks as
begin
merge book b using weeklychange w on b.isbn=w.isbn
when not matched then
insert values (w.isbn,w.price,w.shelf)
when matched and (w.isbn!=b.isbn or w.price!=b.price or w.shelf!=b.shelf) then
update set b.isbn=w.isbn , b.price=w.price,b.shelf=w.shelf
output $action,inserted.*,deleted.*,sysdatetime() into bookhistory;
end
insert into weeklychange values('SQL程序设计',89,1)
select * from book
select * from weeklychange
select * from bookhistory
/*
isbn price shelf
-------------------- --------------------------------------- -----------
(0 行受影响)
isbn price shelf
-------------------- --------------------------------------- -----------
SQL程序设计 89 1
(1 行受影响)
Action newISBN newprice newshelf oldisbn oldprice oldshelf archivedat
---------- -------------------- --------------------------------------- ----------- -------------------- --------------------------------------- ----------- ----------------------
(0 行受影响)
*/
execute uspupdatebooks
select * from book
select * from weeklychange
select * from bookhistory
/*
isbn price shelf
-------------------- --------------------------------------- -----------
SQL程序设计 89 1
(1 行受影响)
isbn price shelf
-------------------- --------------------------------------- -----------
SQL程序设计 89 1
(1 行受影响)
Action newISBN newprice newshelf oldisbn oldprice oldshelf archivedat
---------- -------------------- --------------------------------------- ----------- -------------------- --------------------------------------- ----------- ----------------------
INSERT SQL程序设计 89 1 NULL NULL NULL 2012-12-05 14:19:12.29
(1 行受影响)
*/
*作者：Stephenzhou(阿蒙)
*日期: 2012.12.5
*Mail:szstephenzhou@163.com
*另外：转载请著名出处。
*博客地址：http://blog.csdn.net/szstephenzhou
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