Question

I use this code to check if an element of the new entry is equal to an element of previously inserted data.

CREATE TRIGGER trig1 ON Table1

AFTER INSERT

AS

DECLARE trigcursor CURSOR FOR
SELECT Name FROM INSERTED

DECLARE @Name1 varchar(80)

OPEN trigcursor;

FETCH NEXT FROM trigcursor INTO @Name1

WHILE @@FETCH_STATUS = 0
BEGIN
IF EXISTS(SELECT * FROM Table1 WHERE Name= @Name1)
BEGIN 
    ...
    END
    FETCH NEXT FROM trigcursor INTO @Name1
END

The problem is that for some reason the new entry exists also in the table Table1, not only in INSERTED. So the condition is always true. Can you help me why this happens? Is there a way to retrieve only the initial table without the new entry in it? Thanks!

Answer 1

Your trigger is AFTER INSERT on table Table1. It should be BEFORE INSERT if you expect not to find the record in the table.

Alternative: use INSTEAD OF INSERT trigger.

OR

Add another column that accepts null. Make it a number column so that it will be fast. Do not insert any value in it on the insert. Then, in the AFTER INSERT TRIGGER, the rows that have that column empty are the new ones. The ones that have the column filled with something are the old ones.
Then update empty columns with value.

eg: add column mark
After insert, look for the name:

SELECT * FROM Table1 WHERE Name= @Name1 and mark is not null

Once you found out whether or not it existed before, update everything with something:

update table1 set mark = 1 where mark is null