IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
               WHERE SYSCOLUMNS.NAME = 'SMSGONDERILDI_ISTDR' AND SYSOBJECTS.name = 'HTETKIK')
ALTER TABLE dbo.HTETKIK ADD SMSGONDERILDI_ISTDR BIT null
GO