using (MTSEntities entities = new MTSEntities()) { string queryStr = @"select b.UserName as UserName, SqlServer.AVG(SqlServer.DATEDIFF('year', a.BirthDay, SqlServer.getDate())) as ArgAge from MTS_CaseInfo as a inner join MTS_Doctor as b on a.Account = b.Account group by b.UserName"; ObjectQuery<ReportGender> query = entities.CreateQuery<ReportGender> (queryStr);