IF  EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
              WHERE SYSCOLUMNS.NAME = 'TANIMI' AND SYSOBJECTS.name = 'HYATISBESLENME')
ALTER TABLE dbo.HYATISBESLENME ALTER COLUMN [TANIMI] varchar(500) NULL 
GO
