IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
               WHERE SYSCOLUMNS.NAME = 'KULLANILANDAMLA' AND SYSOBJECTS.name = 'HMUAYENEEK2900')

ALTER TABLE HMUAYENEEK2900
	ADD KULLANILANDAMLA nvarchar(50)
GO