public static bool Update(InvoiceInformation invoice)
 {
     try
     {
         db.Entry(invoice).State = System.Data.Entity.EntityState.Modified;
         db.SaveChanges();
         return true;
     }
     catch (Exception ex)
     {
         return false;
         throw;
     }
 }
 public static bool Insert(InvoiceInformation invoice)
 {
     try
     {
         db.InvoiceInformation.Add(invoice);
         db.SaveChanges();
         return true;
     }
     catch (Exception ex)
     {
         return false;
         throw;
     }
 }