IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
               WHERE SYSCOLUMNS.NAME = 'TCKIMLIKNO' AND SYSOBJECTS.name = 'TSAGLIKP')
ALTER TABLE dbo.TSAGLIKP ADD
    TCKIMLIKNO NVARCHAR(11)
GO