How to create a trigger that uses INSERT , DELETE , UPDATE events - sql

I want to create a trigger for logging.So i need event names of INSERT,UPDATE or DELETE.i.e : one of these statements is used in query execution my trigger will trig and starts logging.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER LogBuses
ON Bus_table
AFTER INSERT,DELETE
AS
BEGIN
DECLARE #PlateNo nvarchar(50)
IF INSERT//something like that-INSERTING- DELETING
SELECT #PlateNo=PlateNo from inserted
insert into Logger (EffectedTable,ActionName,EffectDate,EffectedID)
VALUES ('Bus_table','Insert',SYSDATETIME (),#PlateNo);
ELSE IF DELETE
SELECT #PlateNo=PlateNo from deleted
insert into Logger (EffectedTable,ActionName,EffectDate,EffectedID) VALUES ('Bus_table','Insert',SYSDATETIME (),#PlateNo);
END
GO

You use the inserted and deleted tables. It's inserted if just the inserted table is populated, deleted if just the deleted table is populated, and updated if both tables are populated. Use if exists (select 1 from inserted) to test.
if exists (select 1 from inserted) and exists (select 1 from deleted)
--update
else if exists (select 1 from inserted)
--insert
else if exists (select 1 from deleted)
--delete

Create a stored procedure that logs, and triggers for each event, that call the procedure, passing the needed data.

Related

AUDIT TRAIL OF TABLES

I want to do audit trail on specific table like
what inserted,updated,deleted in table and all this logs are save in one table
I am using sql server 2012 .
Can any one please help me with how to achieve this?
Please note - Use of cursor is restricted
create an after trigger on that table and insert the records into the log table .
create trigger <trigger_name> after insert/update/delete/ on
table <orig table>
begin
insert into the log tables ('all the fields that you require');
end
Try using CDC (Change Data Capture). A very helpful tool which will help to manage the Audit Trail
Read the article from MSDN
This can be achieve using Triggers. Trigger will make your DML operations slower, if large Insert, Delete and Update operations are happening on your table. If it's small table you can create TRIGGER like below, to log the rows to another table based on the action occurred.
You can make use of Inserted and Deleted magic tables which hold the rows which are being Inserted and Deleted inside a trigger.
There is another alternate if you need more control over auditing using CDC (Change Data Capture).
CREATE TABLE TrailTable
(
Id INT,
Name VARCHAR(100)
);
CREATE TABLE TrailTableLog
(
Id INT,
Name VARCHAR(100),
Action CHAR(3)
);
Insert Into TrailTable VALUES (1,'Vi');
Insert Into TrailTable VALUES (2,'Vr');
Insert Into TrailTable VALUES (3,'An');
Insert Into TrailTable VALUES (4,'Ma');
CREATE TRIGGER dbo.TRG_IDU_TrailTable
ON dbo.TrailTable
AFTER INSERT, UPDATE, DELETE
AS
BEGIN
SET NOCOUNT ON;
DECLARE #Action as char(1);
SET #Action = (CASE WHEN EXISTS(SELECT * FROM INSERTED)
AND EXISTS(SELECT * FROM DELETED)
THEN 'U' -- Set Action to Updated.
WHEN EXISTS(SELECT * FROM INSERTED)
THEN 'I' -- Set Action to Insert.
WHEN EXISTS(SELECT * FROM DELETED)
THEN 'D' -- Set Action to Deleted.
ELSE NULL -- Skip. It may have been a "failed delete".
END)
IF(#Action = 'I')
BEGIN
INSERT INTO TRG_IDU_TrailTable (Id, Name, Action)
SELECT Id, Name, 'I' FROM INSERTED;
END
IF(#Action = 'D')
BEGIN
INSERT INTO TRG_IDU_TrailTable (Id, Name, Action)
SELECT Id, Name, 'D' FROM DELETED;
END
IF(#Action = 'U')
BEGIN
INSERT INTO TRG_IDU_TrailTable (Id, Name, Action)
SELECT Id, Name, 'U-D' FROM INSERTED; -- Records Deleted to Update
INSERT INTO TRG_IDU_TrailTable (Id, Name, Action)
SELECT Id, Name, 'U-I' FROM INSERTED; --Records Inserted to Update
END
END

UPDATE after INSERT for potentially multiple rows - not working

I have the following trigger which doesn't work and I'm not sure why.
The trigger should fire after an insert into the REFERRALS table and I've allowed for the possibility of multiple rows being inserted.
The value of ORIGINAL_PATIENT_ID in the REFERRALS table should be set to the value of PATIENT_ID in Inserted, but it just doesn't work, i.e. the value of ORIGINAL_PATIENT_ID remains NULL.
IF EXISTS (SELECT * FROM sys.triggers WHERE object_id = OBJECT_ID(N'[dbo].[updateOSC]'))
DROP TRIGGER [dbo].[updateOSC]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER [dbo].[updateOSC]
ON [dbo].[REFERRALS]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON
IF (SELECT ORIGINAL_PATIENT_ID FROM Inserted) IS NULL
UPDATE [dbo].[REFERRALS]
SET ORIGINAL_PATIENT_ID = i.PATIENT_ID
FROM Inserted i
WHERE dbo.REFERRALS.PATIENT_ID = i.PATIENT_ID
END
GO
If you can have multiple rows being updated then IF (SELECT ORIGINAL_PATIENT_ID FROM Inserted) IS NULL doesn't make much sense to me as this will return multiple values which you cannot compare to NULL.
I think you will get your desired result by using
CREATE TRIGGER [dbo].[updateOSC]
ON [dbo].[REFERRALS]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON
UPDATE [dbo].[REFERRALS]
SET
ORIGINAL_PATIENT_ID = i.PATIENT_ID
FROM
Inserted i
WHERE
dbo.REFERRALS.PATIENT_ID = i.PATIENT_ID AND i.ORIGINAL_PATIENT_ID IS NULL
END
GO

How use inserted\deleted table in stored procedure?

I creating triggers for several tables. The triggers have same logic. I will want to use a common stored procedure.
But I don't know how work with inserted and deleted table.
example:
SET #FiledId = (SELECT FiledId FROM inserted)
begin tran
update table with (serializable) set DateVersion = GETDATE()
where FiledId = #FiledId
if ##rowcount = 0
begin
insert table (FiledId) values (#FiledId)
end
commit tran
You can use a table valued parameter to store the inserted / deleted values from triggers, and pass it across to the proc. e.g., if all you need in your proc is the UNIQUE FileID's:
CREATE TYPE FileIds AS TABLE
(
FileId INT
);
-- Create the proc to use the type as a TVP
CREATE PROC commonProc(#FileIds AS FileIds READONLY)
AS
BEGIN
UPDATE at
SET at.DateVersion = CURRENT_TIMESTAMP
FROM ATable at
JOIN #FileIds fi
ON at.FileID = fi.FileID;
END
And then pass the inserted / deleted ids from the trigger, e.g.:
CREATE TRIGGER MyTrigger ON SomeTable FOR INSERT
AS
BEGIN
DECLARE #FileIds FileIDs;
INSERT INTO #FileIds(FileID)
SELECT DISTINCT FileID FROM INSERTED;
EXEC commonProc #FileIds;
END;
You can
select * into #Inserted from inserted
select * into #Deleted from deleted
and then
use these two temp tables in your stored proc
The tables inserted and deleted are only available inside the trigger. You can only use them in run-time. They will then contain the affected rows.
Also, your code might not work as expected if there is not exactly one row inserted.

Deleted Virtual table in SQL Server is empty ON Delete trigger

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.

Can a storeProcecdure insert fire Trigger?

SQL Server 2008
I have trigger defined on
TABLE_A for 'INSTEAD OF INSERT' and TABLE_B for 'INSTEAD OF INSERT'.
Both the triggers perform merge with the inserted table.
TABLE_A insert is done by user/code and is working well, trigger for insert is fired.
I have Stored procedure SP_1 inside TABLE_A TRIGGER.
SP_1 Inserts data from TABLE_A into TABLE_B based on some conditions.
But the problem is when the stored procedure (SP_1) is inserting data, the trigger on TABLE_B is not fired and the data is just inserted as it is.
So can stored procedure inserts fire triggers?
Pseudo-code
ALTER TRIGGER [dbo].[trgtable_AInsert] ON [dbo].[TABLE_A]
Instead of INSERT
AS
BEGIN
SET NOCOUNT ON;
IF exists(SELECT * FROM INSERTED)
BEGIN
MERGE
.......
...........
..............
end
EXEC SP_1 #employee_id
end
ALTER TRIGGER [dbo].[trgtableB_Insert] ON [dbo].[TABLE_B]
Instead of INSERT
AS
BEGIN
SET NOCOUNT ON;
IF exists(SELECT * FROM INSERTED)
BEGIN
MERGE
.......
...........
..............
end
end
ALTER PROCEDURE [dbo].[SP_1] #employeeid int
AS
BEGIN
BEGIN TRANSACTION
insert into TABLE_B
.......
...........
..............
from TABLE_A
where employee_ID is #employeeid
COMMIT TRANSACTION
END
Yes triggers can fired by stored procedure inserts!
But I think the problem is that you should try to use AFTER instead of INSTEAD OF triggers in this case. Becasue I can't see all of your code, but it is possible, that the insert is not done because you overrided it in the Instead Of triggers. With AFTER triggers you should have no problems with firing the second trigger.
This is too big for a comment, and needs formatting, so posting as an "answer".
Yes, triggers will fire in this case. Taking your example and slightly modifying it (note the warnings though):
create table Table_A (ID int not null)
go
create table Table_B (ID int not null)
GO
CREATE PROCEDURE [dbo].[SP_1] #employeeid int
AS
BEGIN
BEGIN TRANSACTION
insert into TABLE_B (ID)
SELECT ID from TABLE_A
where ID = #employeeid
COMMIT TRANSACTION
END
GO
Creating the triggers:
CREATE TRIGGER [dbo].[trgtable_AInsert] ON [dbo].[TABLE_A]
Instead of INSERT
AS
BEGIN
SET NOCOUNT ON;
IF exists(SELECT * FROM INSERTED)
BEGIN
MERGE
into Table_A a
using inserted i on a.id = i.id
when not matched then insert (ID) values (i.id);
end
--Wrong code, just for example
declare #employee_id int
select #employee_id = ID from inserted --BAD CODE, Ignores multiple rows
EXEC SP_1 #employee_id
end
GO
CREATE TRIGGER [dbo].[trgtableB_Insert] ON [dbo].[TABLE_B]
Instead of INSERT
AS
BEGIN
SET NOCOUNT ON;
IF exists(SELECT * FROM INSERTED)
BEGIN
MERGE
into Table_B b
using inserted i on b.id = i.id
when not matched then insert (ID) values (i.id+5);
end
end
GO
And executing a trial insert into Table_A:
insert into Table_A (ID) values (1),(2)
select * from Table_B
On my machine, at the present time, I get a final result of a single row with the value "7". Others may run this sample and get the result "6", because triggers only run once per statement, rather than once per row. But as you can see, both triggers have fired.
As i previously mentioned in the comments #András Ottó
Merge
using(... = "column with possible null values" AND
... = ... AND
... = ...
)
of merge was not working correctly and the records were always inserted.
1 = 1 and E=E and NULL=NULL is not true. (of-course sql 101)
I have overlooked this column and did not place where clause properly to get rid of null values so ended up inserting all the time. Fixing that everything ended up working.
Thanks for the help Every1. Cheers
Apologies.
I'm not going to mark it answered because it is purely my mistake which was not fully mentioned in the question.