sql-server - update trigger with a condition

Question

I have an update trigger which runs if field 'urejeno' gets modified.

USE [MYDATABASE]
GO

create trigger trg_MyTrigger on dbo.mytable 
after update 
as 
    if @@ROWCOUNT = 0
        return

    set nocount on

    if UPDATE (UREJENO)
       update mytable 
       set UREJENO_KDAJ = getdate(),
           UREDIL_KDO   = USER_NAME()
       from mytable S
       inner join Inserted I on S.TW_ID = I.TW_ID 

However I would like to add a condition so that if 'urejeno' = True the trigger does what is described above but if the condition is 'False' I want to set the mentioned fields to NULL.

What must I change ?

Answer 1

You could add another update query in an else part of the conditional, or you could rewrite your update and use the bit value as the conditional directly.

This should work (if I understood you intent correctly).

CREATE TRIGGER trg_MyTrigger ON dbo.mytable 
AFTER UPDATE 
AS 
    IF @@ROWCOUNT = 0
        RETURN
    SET NOCOUNT ON

    IF UPDATE(UREJENO) 
    BEGIN
    UPDATE mytable 
    SET 
       UREJENO_KDAJ = CASE WHEN I.UREJENO = 1 THEN GETDATE() ELSE NULL END,
       UREDIL_KDO   = CASE WHEN I.UREJENO = 1 THEN USER_NAME() ELSE NULL END
    FROM mytable S
    INNER JOIN Inserted I on S.TW_ID = I.TW_ID 
    END
GO

This would set the two fields to null if UREJENO was updated to 0 (false), but UREJENO was set to 1 (true) then getdate() and user_name() would be used.