Audit trigger inserting multiple rows into audit table - sql

Question

I have written a trigger and when I update a value in the base table, I get more than one record in my audit table. I'm expecting just one. Here's my trigger:
CREATE TRIGGER dbo.SOP10100_TRDISAMT
ON dbo.SOP10100
AFTER INSERT, UPDATE
AS
BEGIN
SET NOCOUNT ON;
IF (select TRDISAMT from inserted) = 0
BEGIN
RETURN
END
ELSE
BEGIN
DECLARE #SOPTYPE smallint = (select soptype from inserted)
DECLARE #SOPNUMBE char(21) = (select sopnumbe from inserted)
DECLARE #MSTRNUMB int = (select mstrnumb from inserted)
DECLARE #DOCID char(15) = (select docid from inserted)
DECLARE #SUBTOTAL numeric(19,5) = (select subtotal from inserted)
DECLARE #MISCAMT numeric(19,5) = (select MISCAMNT from inserted)
DECLARE #TRDISAMT numeric(19,5) = (select TRDISAMT from inserted)
DECLARE #TRDISAMT_B4 numeric(19,5) = (select TRDISAMT from deleted)
DECLARE #FRTAMNT numeric(19,5) = (select FRTAMNT from inserted)
DECLARE #TAXAMNT numeric(19,5) = (select TAXAMNT from inserted)
DECLARE #DOCAMNT numeric(19,5) = (select DOCAMNT from inserted)
DECLARE #USERNAME nvarchar(128) = (select SUSER_SNAME())
DECLARE #TheTime datetime = (select GETDATE())
INSERT INTO SOP10100_TRDISAMT_AUDIT (soptype,sopnumbe,MSTRNUMB,DOCID,SUBTOTAL,MISCAMT,TRDISAMT,TRDISAMT_B4,FRTAMNT,TAXAMNT,DOCAMNT,USERNAME,TheTime)
VALUES (#SOPTYPE,#SOPNUMBE,#MSTRNUMB,#DOCID,#SUBTOTAL,#MISCAMT,#TRDISAMT,#TRDISAMT_B4,#FRTAMNT,#TAXAMNT,#DOCAMNT,#USERNAME,#TheTime)
END
END
and here is what I run to update the value:
update SOP10100 set TRDISAMT = 35 where SOPTYPE = 1 and SOPNUMBE = '126535'
This results in two records being inserted into my audit table. Thoughts?

Answer 1

Your query is fatally flawed, because it does not take into account multiple (or zero) rows being inserted or updated.
Your trigger should probably look something like this:
CREATE TRIGGER dbo.SOP10100_TRDISAMT
ON dbo.SOP10100
AFTER INSERT, UPDATE
AS
INSERT INTO SOP10100_TRDISAMT_AUDIT
(soptype, sopnumbe, MSTRNUMB, DOCID, SUBTOTAL, MISCAMT, TRDISAMT,
TRDISAMT_B4, FRTAMNT, TAXAMNT, DOCAMNT, USERNAME, TheTime)
SELECT i.soptype, i.sopnumbe, i.mstrnumb, i.docid, i.subtotal, i.MISCAMNT, i.TRDISAMT,
i.TRDISAMT, i.FRTAMNT, i.TAXAMNT, i.DOCAMNT, SUSER_SNAME(), GETDATE()
FROM inserted i
WHERE i.TRDISAMT <> 0;
GO
If you want to exclude rows where the values have not been changed at all by the UPDATE statement, you need to add
EXCEPT
SELECT d.soptype, d.sopnumbe.....
FROM deleted d
I note that char is an unusual data type, and should only be used where the value is fixed at that length, otherwise you will get trailing spaces.