Reduce stock quantity

public bool AddOrder(OrderViewModel objOrderViewModel)
{
    tblOrder objOrder = new tblOrder();
    objOrder.CustomerId = objOrderViewModel.CustomerId;
    objOrder.FinalTotal = objOrderViewModel.FinalTotal;
    objOrder.OrderDate = DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss");
    objOrder.OrderNumber = string.Format("{0:ddmmmyyyyhhmmss }", DateTime.Now);
    objOrder.PaymentTypeId = objOrderViewModel.PaymentTypeId;
    objRestaurantDBEntities.tblOrders.Add(objOrder);
    objRestaurantDBEntities.SaveChanges();
    int OderId = objOrder.OderId;

    foreach (var item in objOrderViewModel.ListofOrderDetailViewModel)
    {
        tblOrderDetail objOrderDetails = new tblOrderDetail();
        objOrderDetails.OderId = OderId;
        objOrderDetails.Discount = item.Discount;
        objOrderDetails.ItemId = item.ItemId;
        objOrderDetails.Total = item.Total;
        objOrderDetails.UnitPrice = item.UnitPrice;
        objOrderDetails.Quantity = item.Quantity;
        objRestaurantDBEntities.tblOrderDetails.Add(objOrderDetails);
        objRestaurantDBEntities.SaveChanges();

        // Fetch the current quantity of the item
        var existingQuantity = objRestaurantDBEntities.tblQuantities.FirstOrDefault(q => q.ItemId == item.ItemId);

        if (existingQuantity != null)
        {
            // Calculate the new quantity after sale
            existingQuantity.Quantity -= item.Quantity;
            objRestaurantDBEntities.SaveChanges();
        }
        else
        {
             
        }
    }
    return true;
}

Here's a revised code that fetches the current quantity of each item and then updates the quantity after the sale:

Thank you team, it is working now

It seems like you want to reduce the stock quantity by the sales quantity when an order is placed. However, in your current code, you’re creating a new tblQuantity object each time, which is not correct. You should instead fetch the existing quantity for the item and then reduce it. Here’s how you can modify your code:

public bool AddOrder(OrderViewModel objOrderViewModel)
{
    tblOrder objOrder = new tblOrder();
    // ... existing code ...

    foreach (var item in objOrderViewModel.ListofOrderDetailViewModel)
    {
        tblOrderDetail objOrderDetails = new tblOrderDetail();
        // ... existing code ...

        // Fetch the existing quantity for the item
        tblQuantity objtblQuantity = objRestaurantDBEntities.tblQuantity.FirstOrDefault(q => q.ItemId == item.ItemId);
        if (objtblQuantity != null)
        {
            // Reduce the quantity
            objtblQuantity.Quantity -= item.Quantity;

            // Save the changes
            objRestaurantDBEntities.SaveChanges();
        }
        else
        {
            // Handle the case where no quantity record exists for the item
            // ...
        }
    }
    return true;
}

This code fetches the existing tblQuantity record for the item, reduces the quantity by the sales quantity, and then saves the changes. If no tblQuantity record exists for the item, you’ll need to decide how to handle that case. For example, you might want to create a new record with a default quantity, or show an error message. Please replace the // ... with your own code. I hope this helps! 

Thanks

Try this:

public bool AddOrder(OrderViewModel objOrderViewModel)
{
    tblOrder objOrder = new tblOrder();
    objOrder.CustomerId = objOrderViewModel.CustomerId;
    objOrder.FinalTotal = objOrderViewModel.FinalTotal;
    objOrder.OrderDate = DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss");
    objOrder.OrderNumber = string.Format("{0:ddmmmyyyyhhmmss }", DateTime.Now);
    objOrder.PaymentTypeId = objOrderViewModel.PaymentTypeId;
    objRestaurantDBEntities.tblOrders.Add(objOrder);
    objRestaurantDBEntities.SaveChanges();
    int OderId = objOrder.OderId;

    foreach (var item in objOrderViewModel.ListofOrderDetailViewModel)
    {
        tblOrderDetail objOrderDetails = new tblOrderDetail();
        objOrderDetails.OderId = OderId;
        objOrderDetails.Discount = item.Discount;
        objOrderDetails.ItemId = item.ItemId;
        objOrderDetails.Total = item.Total;
        objOrderDetails.UnitPrice = item.UnitPrice;
        objOrderDetails.Quantity = item.Quantity;
        objRestaurantDBEntities.tblOrderDetails.Add(objOrderDetails);
        objRestaurantDBEntities.SaveChanges();

        // Modified Code For Update Quantity
        tblQuantity objtblQuantity = objRestaurantDBEntities.tblQuantity.FirstOrDefault(q => q.ItemId == item.ItemId);
        if (objtblQuantity != null)
        {
            objtblQuantity.Quantity -= item.Quantity;
            
            objRestaurantDBEntities.Entry(objtblQuantity).State = EntityState.Modified;
            objRestaurantDBEntities.SaveChanges();
        }
        else
        {
            throw new Exception("Item's quantity record not found in the database.");
        }
    }
    return true;
}

To reduce the stock quantity by the sales quantity in a Dot Net application, you can follow these steps:

1. Retrieve the sales quantity from the order details.
2. Subtract the sales quantity from the current stock quantity.
3. Update the stock quantity in the database.

Here's an example of how you can implement this in your code:

foreach (var item in objOrderViewModel.ListofOrderDetailViewModel)
{
    // Retrieve the sales quantity from the order details
    int salesQuantity = item.Quantity;

    // Get the current stock quantity from the database
    tblQuantity objtblQuantity = objRestaurantDBEntities.tblQuantity.FirstOrDefault(q => q.ItemId == item.ItemId);

    if (objtblQuantity != null)
    {
        // Subtract the sales quantity from the current stock quantity
        objtblQuantity.Quantity -= salesQuantity;

        // Update the stock quantity in the database
        objRestaurantDBEntities.SaveChanges();
    }
}