IF  EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
              WHERE SYSCOLUMNS.NAME = 'BIRIM' AND SYSOBJECTS.name = 'HTETKIKDETAYORNEKTEKRAR')
ALTER TABLE dbo.HTETKIKDETAYORNEKTEKRAR ALTER COLUMN [BIRIM] varchar(30) NULL 
go
