string entitySQL = "SELECT VALUE u FROM Users AS u WHERE EXISTS(SELECT p FROM Users AS p WHERE p.Roleid = 0);";                var query = ObjectContext.CreateQuery
      
       (entitySQL);
      

 

using (var ObjectContext = new AgentSystemEntities())            {                DateTime dt = new DateTime(1997, 1, 1);                string entitySQL = "SELECT VALUE Users FROM Users WHERE Users.AddDateTime > @dt;";                ObjectParameter[] ps = { new ObjectParameter("dt", dt) };                ObjectQuery
     
       query = ObjectContext.CreateQuery
      
       (entitySQL,ps);                string message = "执行的语句:" + query.CommandText + "\n\r";                if (query.Count() > 0)                {                    message += query.First().UserNames + "\n\r";                }                else                {                    message += "没有数据\n\r";                }                MessageBox.Show(message);            }