IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
               WHERE SYSCOLUMNS.NAME = 'HWEBSIFRETARIHI' AND SYSOBJECTS.name = 'HKIMLIK')
ALTER TABLE dbo.HKIMLIK ADD
	HWEBSIFRETARIHI DATETIME NULL
GO