public PurchaseTableCollection FetchAll()
 {
     PurchaseTableCollection coll = new PurchaseTableCollection();
     Query qry = new Query(PurchaseTable.Schema);
     coll.LoadAndCloseReader(qry.ExecuteReader());
     return coll;
 }
 public PurchaseTableCollection FetchByQuery(Query qry)
 {
     PurchaseTableCollection coll = new PurchaseTableCollection();
     coll.LoadAndCloseReader(qry.ExecuteReader()); 
     return coll;
 }
 public PurchaseTableCollection FetchByID(object Id)
 {
     PurchaseTableCollection coll = new PurchaseTableCollection().Where("ID", Id).Load();
     return coll;
 }