IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
              WHERE SYSCOLUMNS.NAME = 'TSS' AND SYSOBJECTS.name = 'TDRCALSAAT')
ALTER TABLE TDRCALSAAT ADD TSS INT NOT NULL CONSTRAINT [DF_TDRCALSAAT_TSS] DEFAULT (0)
GO
