Create trigger to increase value when found duplicate - sql-server-2008

Question

I need to make trigger to increase the 2nd digit when the new value found to be a duplicate.
For Instance, I have a unique filed with 10 digits value. I want when someone insert same number it increase the second left digit like 0100012345. How I can do that? Thank you.
FirstName LastName Code
Houssam Salim 0100012345 to be 0200012345

Answer 1

Try this
I have found a solution with instead off trigger
'/*
CREATE TABLE [Employee1]
(
[id] VARCHAR(20) PRIMARY KEY,
[name] VARCHAR(50)
)
CREATE TRIGGER AutoIncrement_Trigger
ON [Employee1]
instead OF INSERT
AS
BEGIN
DECLARE #ch CHAR
DECLARE #num INT
IF EXISTS (SELECT 1
FROM Employee1 e
JOIN inserted i
ON i.id = e.id)
BEGIN
SET #num=(SELECT max(CONVERT(INT, substring(e.id, 1, 2))) + 1
FROM employee1 e
JOIN inserted i
ON substring(e.id, 3, len(e.id)) = substring(i.id, 3, len(i.id)))
INSERT INTO [Employee1]
(id,
name)
SELECT '0' + CONVERT(VARCHAR(10), #num)
+ substring(i.id, 3, len(i.id)),
e.name
FROM Employee1 e
JOIN inserted i
ON i.id = e.id
END
ELSE
BEGIN
INSERT INTO [Employee1]
(id,
name)
SELECT inserted.id,
inserted.name
FROM inserted
END
END
*/
INSERT INTO [Employee1]
VALUES ('0100012345',
'John')
SELECT *
FROM [Employee1]
INSERT INTO [Employee1]
VALUES ('0100012345',
'John')
SELECT *
FROM [Employee1]
'