Inserting Data into multiple SQL tables with foreign key constraints using C#

Question

As the title suggests, I am looking for solutions to add data to multiple tables that have FK constraints all on one form.

Basically I click the magic button and it fires the data over to the relevant tables. See the screenshot for table relationships so you can see the general idea:

enter image description here

I am getting this error:

Cannot insert NULL into BookingID

for the Payments table. This is a FK relationship, but basically when I press Enter on the Windows form, I want it to generate the primary key in the Booking table and link it so it saves it all as one booking.

I have inserted an image of the actual booking screen (it's very basic at the moment) but it highlights the tables etc.

I am trying to figure out how i can explain this in a better way, so sorry if it is not very clear. But Basically, The bookings table has CustomerID and PaymentsID FK's in it. When I press enter, I want it to send the data over so that if I ran a query on the specific booking ID it would display all the information (Cust name, Payments etc).

Oh and I am doing the Windows Forms in C# which I am very very new to so please be gentle with me.

I was asked to upload some code so here is a little bit. The problem I have is I have no idea how to handle FK constraints using C#.

using (var cmd = new SqlCommand("INSERT INTO Payments (PaymentMethod, PaymentAmount, PaymentDate, PaymentReceived, Discount) VALUES (@PayMethod,@Cost,@PayDate,@PaymentReceived,@Discount)"))
{
    cmd.Connection = con;

    cmd.Parameters.Add("@PayMethod", SqlDbType.VarChar).Value = PayMeth.Text;
    cmd.Parameters.Add("@Cost", SqlDbType.Money).Value = Cost.Text;
    cmd.Parameters.Add("@PayDate", SqlDbType.DateTime).Value = PayDatePick.Text;
    cmd.Parameters.Add("@PaymentReceived", SqlDbType.VarChar).Value = PayReceived.Text;
    cmd.Parameters.Add("@Discount", SqlDbType.VarChar).Value = DiscountText.Text;

    if (cmd.ExecuteNonQuery() > 0)
    {
        MessageBox.Show("Record inserted");
    }
    else
    {
        MessageBox.Show("Payment failed");
    }
}

Answer 1

Is your Booking.BookingId an auto increment or Unique field?

If not when you insert the booking record, you will need to set the value (so its not null).