/// <summary>
        /// Returns true if OrderItem instances are equal
        /// </summary>
        /// <param name="other">Instance of OrderItem to be compared</param>
        /// <returns>Boolean</returns>
        public bool Equals(OrderItem other)
        {
            if (ReferenceEquals(null, other))
            {
                return(false);
            }
            if (ReferenceEquals(this, other))
            {
                return(true);
            }

            return
                ((
                     ItemName == other.ItemName ||
                     ItemName != null &&
                     ItemName.Equals(other.ItemName)
                     ) &&
                 (
                     Qty == other.Qty ||
                     Qty.Equals(other.Qty)
                 ) &&
                 (
                     UnitPrice.Equals(other.UnitPrice)
                 ) &&
                 (
                     Cost.Equals(other.Cost)
                 ));
        }
 protected bool Equals(PurchaseOrderLine other)
 {
     return(PurchaseOrderId == other.PurchaseOrderId && RawMaterialId == other.RawMaterialId &&
            SupplierId == other.SupplierId && UnitPrice.Equals(other.UnitPrice) &&
            Quantity.Equals(other.Quantity) && string.Equals(UnitOfMeasure, other.UnitOfMeasure));
 }