IF NOT Exists(SELECT *
                FROM sysindexes SI
                     INNER JOIN sysobjects SO
                             ON SO.[id] = SI.[id]
                            AND so.[name] = 'diary'
               WHERE SI.[name] = 'KeyEmailDates')
BEGIN
  CREATE NONCLUSTERED INDEX 
         [KeyEmailDates]
      ON [dbo].[diary] 
        ([EMAIL]          ASC,
         [TxmDate]        ASC,
         [DATE]           ASC)
      ON [PRIMARY]
END
GO