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sum function

Author

Topic

taniarto
Starting Member

27 Posts

Posted - 2013-09-27 : 21:58:22

Dear All,

I have 2 tables :
1. Table sales

ID item qty
001 ICe 20
002 Book 10
003 Book 20

2. Table Stock

ID qty
001 20
002 30

I create a trigger on Sales Table :

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

ALTER TRIGGER [insert_sales] ON [dbo].[sales]
for INSERT,update
AS
declare @id_ varchar(20)
declare @qty int

IF EXISTS(
SELECT id
FROM sales where id=@id )
begin
update s
set s.qty=i.qty from stock s
join
(select id,sum(qty) as qty from inserted group by id) i
on s.id=i.id
end

the trigger is running but the result only show the latest record not all of the sum calculation.

The result show :

ID Qty
002 20

not 30 ( as all record result)

Please help..
thanks

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-09-28 : 05:53:12

why do need IF EXISTS? isnt below enough?


ALTER TRIGGER [insert_sales] ON [dbo].[sales] 
for INSERT,update 
AS


update s 
set s.qty=i.qty from stock s
join 
(select id,sum(qty) as qty from inserted group by id) i
on s.id=i.id

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs

taniarto
Starting Member

27 Posts

Posted - 2013-09-30 : 04:02:05

If the record were deleted, is it calculated into the new calculation?
or we must make a delete trigger too?

thanks

quote:
Originally posted by visakh16

why do need IF EXISTS? isnt below enough?

ALTER TRIGGER [insert_sales] ON [dbo].[sales]
for INSERT,update
AS

update s
set s.qty=i.qty from stock s
join
(select id,sum(qty) as qty from inserted group by id) i
on s.id=i.id

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-09-30 : 06:20:22

quote:
Originally posted by taniarto

If the record were deleted, is it calculated into the new calculation?
or we must make a delete trigger too?

thanks

quote:
Originally posted by visakh16

why do need IF EXISTS? isnt below enough?

ALTER TRIGGER [insert_sales] ON [dbo].[sales]
for INSERT,update
AS

update s
set s.qty=i.qty from stock s
join
(select id,sum(qty) as qty from inserted group by id) i
on s.id=i.id

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs

current logic doesnt account deletes

if you want to include it too make trigger like


ALTER TRIGGER [insert_sales] ON [dbo].[sales] 
for INSERT,update ,Delete
AS


update s 
set s.qty=s.qty + i.qty - d.qty  from stock s
left join 
(select id,sum(qty) as qty from inserted group by id) i
on s.id=i.id 
left join 
(select id,sum(qty) as qty from deleted group by id) d
on s.id=d.id

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs

SwePeso
Patron Saint of Lost Yaks

30421 Posts

Posted - 2013-09-30 : 08:36:12

You need a MERGE, because what happens when you delete the last row from Sales?

ALTER TRIGGER	dbo.trgSales
ON		dbo.Sales 
AFTER		INSERT,
		UPDATE,
		DELETE
AS

SET NOCOUNT ON;

MERGE	dbo.Stock AS tgt
USING	(
		SELECT		ID,
				SUM(Qty) AS Qty
		FROM		dbo.Sales
		GROUP BY	ID
	) AS src ON src.ID = tgt.ID
WHEN	MATCHED AND tgt.Qty <> src.Qty
		THEN	UPDATE
			SET	tgt.Qty = src.Qty
WHEN	NOT MATCHED BY TARGET
		THEN	INSERT	(
					ID,
					Qty
				)
			VALUES	(
					src.ID,
					src.Qty
				)
WHEN	NOT MATCHED BY SOURCE
		THEN	DELETE;

Microsoft SQL Server MVP, MCT, MCSE, MCSA, MCP, MCITP, MCTS, MCDBA

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