IF NOT EXISTS (SELECT * FROM SYSCOLUMNS INNER JOIN SYSOBJECTS ON SYSOBJECTS.id = SYSCOLUMNS.id 
              WHERE SYSCOLUMNS.NAME = 'TIPI' AND SYSOBJECTS.name = 'HYATISZIYARETCI')
ALTER TABLE dbo.[HYATISZIYARETCI] ADD TIPI  nvarchar(20) NULL
go