Hi,
I have a DimProduct and StagingProduct tables.
I have a trigger that checks if the record (in staging) to be inserted/updated to DW overlaps with the record in DW.
The trigger works perfectly if i run using update statement. But couldn't run properly when I'm doing merge.
Please help.
/*create tables and records */
CREATE TABLE [dbo].[DimProduct](
[ProductKey] [int] IDENTITY(1,1) NOT NULL,
[ProductID] [smallint] NOT NULL,
[Description] [varchar](50) NOT NULL,
[SubProductID] [int] NOT NULL,
[ValidFrom] [date] NOT NULL,
[ValidTo] [date] NOT NULL
) ON [PRIMARY]
CREATE TABLE [dbo].[StagingProduct](
[ProductID] [smallint] NOT NULL,
[Description] [varchar](50) NOT NULL,
[SubProductID] [int] NOT NULL,
[ValidFrom] [date] NOT NULL,
[ValidTo] [date] NOT NULL
) ON [PRIMARY]
insert into dbo.StagingProduct values (1, 'Pencil', 1, '2013-01-01', '2013-03-05')
insert into dbo.StagingProduct values (1, 'Pencil', 1, '2013-03-06', '2013-06-10')
insert into dbo.StagingProduct values (2, 'IPhone', 2, '2011-01-02', '2012-07-10')
/*trigger for DimProduct*/
CREATE TRIGGER [dbo].[Trigger_ChannelCheck] ON [dbo].[DimProduct]
INSTEAD OF INSERT, UPDATE
AS
IF NOT EXISTS(
SELECT a.SubProductID
FROM
(SELECT aa.SubProductID, aa.ValidFrom, aa.ValidTo, aa.ProductID
FROM dbo.DimProduct aa
WHERE NOT EXISTS (select ProductKey
FROM inserted
WHERE SubProductID = aa.SubProductID AND
ValidFrom = aa.ValidFrom AND
ProductID = aa.ProductID)
) a
INNER JOIN (SELECT SubProductID, ValidFrom, ValidTo, ProductID
FROM inserted) b ON a.SubProductID = b.SubProductID
WHERE b.ValidFrom <= a.ValidTo and b.ValidTo >= a.ValidFrom
)
BEGIN
UPDATE b
SET b.Description = a.Description,
b.ValidTo = a.ValidTo
FROM inserted a
INNER JOIN dbo.DimProduct b ON a.SubProductID = b.SubProductID AND
a.ValidFrom = b.ValidFrom AND
a.ProductID = b.ProductID
INSERT INTO dbo.DimProduct
([ProductID]
,[Description]
,[SubProductID]
,[ValidFrom]
,[ValidTo]
)
SELECT [ProductID]
,[Description]
,[SubProductID]
,[ValidFrom]
,[ValidTo]
FROM inserted a
WHERE NOT EXISTS (SELECT 1
FROM dbo.DimProduct
WHERE SubProductID = a.SubProductID AND
ProductID = a.ProductID AND
ValidFrom = a.ValidFrom)
END
ELSE
ROLLBACK
/*execute merge to load staging to dw */
MERGE dbo.DimProduct AS trget
USING (SELECT *
FROM StagingProduct a
) as src
ON (trget.[SubProductID] = src.[SubProductID] and
trget.[ProductID] = src.[ProductID] and
trget.ValidFrom = src.ValidFrom
)
WHEN NOT MATCHED BY TARGET THEN
INSERT ([ProductID]
,[Description]
,[SubProductID]
,[ValidFrom]
,[ValidTo]
)
VALUES (src.[ProductID]
,src.[Description]
,src.[SubProductID]
,src.[ValidFrom]
,src.[ValidTo]
)
WHEN MATCHED THEN
UPDATE
SET trget.Description = src.Description,
trget.ValidTo = src.ValidTo;
/* error triggers when this is executed. */
update dbo.DimProduct
set validto = '2013-03-12'
where validfrom = '2013-01-01'
/*modify the validto of the record to create an overlap */
update dbo.StagingProduct
set validto = '2013-03-12'
where validfrom = '2013-01-01'
/* if merge is run, the trigger does not behave as it should. no error is raised */
MERGE dbo.DimProduct AS trget
USING (SELECT *
FROM StagingProduct a
) as src
ON (trget.[SubProductID] = src.[SubProductID] and
trget.[ProductID] = src.[ProductID] and
trget.ValidFrom = src.ValidFrom
)
WHEN NOT MATCHED BY TARGET THEN
INSERT ([ProductID]
,[Description]
,[SubProductID]
,[ValidFrom]
,[ValidTo]
)
VALUES (src.[ProductID]
,src.[Description]
,src.[SubProductID]
,src.[ValidFrom]
,src.[ValidTo]
)
WHEN MATCHED THEN
UPDATE
SET trget.Description = src.Description,
trget.ValidTo = src.ValidTo;cherriesh