public class Table
    {
        [Key]
        public int? TableID { get; set; }
        [NotMapped]
        public DateTime? DateCreate { get; set; }
    }

var query =
{
   from x in db.Tables
   select new
   {
      x.DateCreate
   }
}

The specified type member 'DateCreate' is not supported in LINQ to Entities. 
Only initializers, entity members, and entity navigation properties are supported.