I created a trigger in SQL Server 2005 that inserts records into a history table whenever a deletion occurs in the source table. The records are getting inserted, but they are not getting deleted from the source table.
Here is my trigger:
CREATE TRIGGER TRG_EdiHistory
ON dbo.EDI10000
INSTEAD OF DELETE
AS
BEGIN
SET NOCOUNT ON;
SET IDENTITY_INSERT dbo.EDI10500 ON;
INSERT INTO EDI10500(File_Id, Tp_Id, File_Name, File_Size, File_Data, Rec_Date, Content_Type, Update_Flag)
SELECT
File_Id, Tp_Id, File_Name, File_Size, File_Data,
Rec_Date, Content_Type, Update_Flag
FROM
DELETED
END
GO
I had to use an INSTEAD OF trigger because my tables contains Image type columns.
Please if anyone has any idea why this is happening.
Thank you.
* UPDATE *
CREATE TRIGGER TRG_EdiHistory
ON dbo.EDI10000
INSTEAD OF DELETE
AS
BEGIN
SET NOCOUNT ON;
SET IDENTITY_INSERT dbo.EDI10500 ON;
INSERT INTO EDI10500 ([File_Id],Tp_Id,[File_Name],File_Size
,File_Data,Rec_Date,Content_Type,Update_Flag)
SELECT [File_Id], Tp_Id, [File_Name], File_Size, File_Data,
Rec_Date, Content_Type, Update_Flag
FROM DELETED
DELETE FROM dbo.EDI10000
WHERE EXISTS (SELECT 1
FROM DELETED
WHERE [FILE_ID] = dbo.EDI10000.[File_Id])
END
GO
Instead of Triggers , fire Instead of the triggering action. In your Case this instead of Trigger fires and Inserts data into your history table.
Note this trigger fires instead of the Delete command. So if you also want to Delete rows you will need to add Delete statement inside this trigger.
Having said this I think instead of Instead Trigger if you simply define an After Trigger with same definition as your this instead of trigger will makes things pretty simple. It will delete the rows from table and then insert rows into your history table as you are expecting it to work.
Update
Since you have mentioned you cannot use Image Data type inside an After Trigger in sql server 2005, I am not aware of this limitation. Well in this case you can simply add a delete statement inside your this existing instead of trigger.
DELETE FROM dbo.table
WHERE EXISTS (SELECT 1
FROM deleted
WHERE Pk_Column = table.PK_Column)
Instead of delete replaces the standard action of the DELETE statement.
http://technet.microsoft.com/en-us/library/ms191208(v=sql.105).aspx
Have a look here how to do what you really want:
How to create a before delete trigger in SQL Server?
Related
I was wondering if there is a way to backup a registry within another table after a DELETE statement is executed.
for example if I have the table 'employee' and I execute:
delete from employee where idEmp=1
is there any way to insert the data of that employee into another table called 'employeeBackup'(for example) using a trigger?
You would use a DELETE trigger.
https://learn.microsoft.com/en-us/sql/t-sql/statements/create-trigger-transact-sql
Make sure in your trigger that you reference the deleted virtual table and avoid using any variables because triggers fire once per operation, not once per row.
Here is a basic template you could use.
create trigger MyDeleteTrigger on employee FOR DELETE as
set nocount on;
insert employeeBackup
(
Column1,
Column2
)
select Colum1
, Column2
from deleted
I want to copy the contents of a column into another column in the same table. Therefore, I created this trigger:
ALTER TRIGGER [dbo].[kennscht_copy_to_prodverpt]
ON [dbo].[Stammdaten]
AFTER INSERT
AS
UPDATE Stammdaten
SET PRODVERPT = (SELECT KENNSCHT FROM INSERTED)
WHERE SNR = (SELECT SNR FROM INSERTED);
But when I use an UPDATE on the table to update KENNSCHT to a different value, PRODVERPT is not updated as well. Now, you could argue that is because the trigger is on AFTER INSERT and not AFTER UPDATE, but when I change it so it's triggered by UPDATE and INSERT, whenever I update any row, I get an error message from SQL Server
Cannot update row because it would make the row not unique or update multiple rows (2 rows) [sic]
What is going on here? Either the trigger doesn't do anything, or it's messing up the whole table, making it un-updateable.
Update: I also tried the following trigger:
UPDATE s
SET s.PRODVERPT = i.KENNSCHT
FROM Stammdaten s
INNER JOIN INSERTED i ON i.SNR = s.SNR;
But it has exactly the same behaviour. If I use only AFTER INSERT, nothing changes and if I use AFTER INSERT, UPDATE I get the error message above.
Update 2: There are no multiple rows in the table, I already checked that because I thought it might be connected to the issue.
If you run this trigger as an AFTER UPDATE trigger, it runs recursively, since it always issues another UPDATE statement against the same table, which leads to another execution of the trigger.
To work around this, you either need to make the update trigger an INSTEAD OF UPDATE trigger or test if the KENNSCHT column was modified at all. For the latter you can use the UPDATE() function like this:
ALTER TRIGGER [dbo].[kennscht_copy_to_prodverpt_after_update]
ON [dbo].[Stammdaten]
AFTER UPDATE
AS
BEGIN
SET NOCOUNT ON
IF (UPDATE(KENNSCHT))
BEGIN
UPDATE s
SET s.PRODVERPT = i.KENNSCHT
FROM Stammdaten s
INNER JOIN INSERTED i ON i.SNR = s.SNR
END
END
I am trying to invoke an ON Delete trigger event, but when I try to select row from the Deleted table, it is empty.
Is there any other way to get Id of row on which delete event has fired?
Code:
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
ALTER TRIGGER [audit]
ON [dbo].[S_PARTY]
FOR DELETE
AS
-- Insert statements for trigger here
DECLARE #id nvarchar(50)
SET #id = (Select ROW_ID from deleted )
BEGIN
-- Insert statements for trigger here
INSERT INTO [dbo].[S_AMF_AUDIT_ITEM] (ROW_ID)
VALUES (#id);
END
When trigger fires on this, I am getting error as S_AMF_AUDIT_ITEM doesn't allow null values. So can you please help me this to get Id of table on which delete command executes?
Your trigger is broken.
It doesn't take into account that the DELETE statement might affect zero or more than one rows.
The issue with NULL could occur for the statement DELETE FROM [dbo].[S_PARTY] WHERE 1 = 0.
A fixed version would be
ALTER TRIGGER [audit]
ON [dbo].[S_PARTY]
FOR DELETE
AS
BEGIN
INSERT INTO [dbo].[S_AMF_AUDIT_ITEM]
(ROW_ID)
SELECT ROW_ID
FROM deleted;
END
A trigger can fire for 0..N deleted rows. For example:
delete YourTable
where 1=2
Would run a for delete trigger on YourTable. So a trigger has to be able to deal with zero or multiple rows. Consider rewriting your trigger like:
ALTER TRIGGER [audit] ON [dbo].[S_PARTY] FOR DELETE
AS
INSERT dbo.S_AMF_AUDIT_ITEM
(ROW_ID)
SELECT ROW_ID
FROM deleted
That will work for any number of inserted rows.
Here is one very interesting problem. I am using SQL Server 2008.
I have two triggers on one common table say 'CommonTable'. one trigger is on update and other one is on insert/update/delete.
In first trigger "Trigger1", I do the checks/rollback sometime change the new inserted value based on business logic.
here is sample code
-
CREATE TRIGGER [dbo].[Trigger1] ON [dbo].[CommonTable]
FOR UPDATE
UPDATE [CommonTable]
SET
[StatusCode] = 'New Value'
WHERE
[RecId] = 'rec id value'
In second trigger "Trigger2", I store the new inserted/deleted/updated value from 'CommonTable' table to another table 'CommonTable_History' for history tracking purpose.
here is sample code
-
CREATE TRIGGER [dbo].[Trigger2] ON [dbo].[CommonTable]
FOR INSERT, UPDATE, DELETE
--based on logic read the value from DELETED or INSERTED table and store in other table.
SELECT #RowData = (SELECT * FROM DELETED AS [CommonTable] WHERE [RecId] = #RowRecId FOR XML AUTO, BINARY BASE64 , ELEMENTS)
--and then insert #RowData in 'CommonTable_History' table.
With the help of 'sp_settriggerorder', I have set the order of execution of these triggers, so first "Trigger1" get executed and then "Trigger2".
Second trigger "Trigger2" works well for insert/delete values. It works fine for new inserted value if new inserted values has not been changed by first trigger "Trigger1".
But if in some cases, inserted values has been changed in "Trigger1". say [StatusCode] = 'New Value' and old values was 'Old Value' then "Trigger2" still store the 'Old Value' instead of 'New Value'.
Why because "Trigger1" change the value but that value still has not been store in database and before that "Trigger2" get executed on Insert.
Now my requirement is, here I want to store "New Value".
So I thought, lets make "Trigger2" to use "AFTER" keywords. But "FOR" and "AFTER" behave same could not solve the problem.
Then I thought, lets make "Trigger2" to use "INSTEAD OF" keyword. But "INSTEAD OF" gives following error
"Cannot CREATE INSTEAD OF DELETE or INSTEAD OF UPDATE TRIGGER. This is because the table has a FOREIGN KEY with cascading DELETE or UPDATE."
I can not remove FOREIGN KEY with cascading DELETE or UPDATE for table 'CommonTable'.
Please let me know if you people have any other alternate solution.
-Vikram Gehlot
I think your second trigger needs to use the values from the actual table, not the inserted/deleted tables to populate the log table - inserted/deleted will always have the unaltered, original values, while your altered values will appear in the table. Make the second trigger an "After" trigger, so you will not have to use the sp_settriggerorder. Like this, for example:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER [dbo].[trg_Trig1]
ON [dbo].[TestTable]
FOR INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
update TestTable
set [value] = 10
where [value] = 25
END
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER [dbo].[trg_Trig2]
ON [dbo].[TestTable]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Insert statements for trigger here
insert into log_TestTable
(id, description, [value])
select tt.id, tt.description, tt.[value]
from inserted i
LEFT JOIN TestTable tt
ON tt.id = i.id
END
It may not be the cleanest solution but can you simply combine the two triggers into one? That way both pieces of SQL would know about each other's changes.
Your second trigger appears to me as if it would not work properly is mulitple records are inserted in a set-based operations unloess you use a loop which is poor choice in a trigger. Fix that first!
Instead of select * from deleted, why not join the deleted or inserted table to the original table and take the values from there (except for the id value which you get from deleted or inserted, that should give you the most current values of all fileds and if you add other trigger logic later wil not break.
I'm using Sqlserver express and I can't do before updated trigger. There's a other way to do that?
MSSQL does not support BEFORE triggers. The closest you have is INSTEAD OF triggers but their behavior is different to that of BEFORE triggers in MySQL.
You can learn more about them here, and note that INSTEAD OF triggers "Specifies that the trigger is executed instead of the triggering SQL statement, thus overriding the actions of the triggering statements." Thus, actions on the update may not take place if the trigger is not properly written/handled. Cascading actions are also affected.
You may instead want to use a different approach to what you are trying to achieve.
It is true that there aren't "before triggers" in MSSQL. However, you could still track the changes that were made on the table, by using the "inserted" and "deleted" tables together. When an update causes the trigger to fire, the "inserted" table stores the new values and the "deleted" table stores the old values. Once having this info, you could relatively easy simulate the "before trigger" behaviour.
Can't be sure if this applied to SQL Server Express, but you can still access the "before" data even if your trigger is happening AFTER the update. You need to read the data from either the deleted or inserted table that is created on the fly when the table is changed. This is essentially what #Stamen says, but I still needed to explore further to understand that (helpful!) answer.
The deleted table stores copies of the affected rows during DELETE and
UPDATE statements. During the execution of a DELETE or UPDATE
statement, rows are deleted from the trigger table and transferred to
the deleted table...
The inserted table stores copies of the affected rows during INSERT
and UPDATE statements. During an insert or update transaction, new
rows are added to both the inserted table and the trigger table...
https://msdn.microsoft.com/en-us/library/ms191300.aspx
So you can create your trigger to read data from one of those tables, e.g.
CREATE TRIGGER <TriggerName> ON <TableName>
AFTER UPDATE
AS
BEGIN
INSERT INTO <HistoryTable> ( <columns...>, DateChanged )
SELECT <columns...>, getdate()
FROM deleted;
END;
My example is based on the one here:
http://www.seemoredata.com/en/showthread.php?134-Example-of-BEFORE-UPDATE-trigger-in-Sql-Server-good-for-Type-2-dimension-table-updates
sql-server triggers
T-SQL supports only AFTER and INSTEAD OF triggers, it does not feature a BEFORE trigger, as found in some other RDBMSs.
I believe you will want to use an INSTEAD OF trigger.
All "normal" triggers in SQL Server are "AFTER ..." triggers. There are no "BEFORE ..." triggers.
To do something before an update, check out INSTEAD OF UPDATE Triggers.
To do a BEFORE UPDATE in SQL Server I use a trick. I do a false update of the record (UPDATE Table SET Field = Field), in such way I get the previous image of the record.
Remember that when you use an instead trigger, it will not commit the insert unless you specifically tell it to in the trigger. Instead of really means do this instead of what you normally do, so none of the normal insert actions would happen.
Full example:
CREATE TRIGGER [dbo].[trig_020_Original_010_010_Gamechanger]
ON [dbo].[T_Original]
AFTER UPDATE
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
DECLARE #Old_Gamechanger int;
DECLARE #New_Gamechanger int;
-- Insert statements for trigger here
SELECT #Old_Gamechanger = Gamechanger from DELETED;
SELECT #New_Gamechanger = Gamechanger from INSERTED;
IF #Old_Gamechanger != #New_Gamechanger
BEGIN
INSERT INTO [dbo].T_History(ChangeDate, Reason, Callcenter_ID, Old_Gamechanger, New_Gamechanger)
SELECT GETDATE(), 'Time for a change', Callcenter_ID, #Old_Gamechanger, #New_Gamechanger
FROM deleted
;
END
END
The updated or deleted values are stored in DELETED. we can get it by the below method in trigger
Full example,
CREATE TRIGGER PRODUCT_UPDATE ON PRODUCTS
FOR UPDATE
AS
BEGIN
DECLARE #PRODUCT_NAME_OLD VARCHAR(100)
DECLARE #PRODUCT_NAME_NEW VARCHAR(100)
SELECT #PRODUCT_NAME_OLD = product_name from DELETED
SELECT #PRODUCT_NAME_NEW = product_name from INSERTED
END