Insert Data to Master/Detail table in SQL Server from C# with Foreign key

[ahmed_one]

I need some help to make a order form in C#. My development environment is:

Microsoft Visual Studio 2010 Ultimate
SQL Server Express Edition 2005
Programming Language C#
Sample Database = NorthWind (Tables Orders and OrderDetails)

I've create a form for order entry, which contain a textbox for OrderID, a combobox for Customer, DateTimePickers for OrderDate and ShippedDate and a DataGridView which contains cokumns OrderID (readonly), ProductID, UnitPrice & Quantity.

In the form load event I've the following code:

private void Inv2_Load(object sender, EventArgs e)
{
        SetComb();
        connectionString = ConfigurationManager.AppSettings["connectionString"];
        sqlConnection = new SqlConnection(connectionString);

        qryOrd = "Select OrderID, CustomerID, OrderDate, ShippedDate from Orders";
        qryOrdDet = "Select OrderID, ProductID, UnitPrice, Quantity from OrderDetails";

        sqlConnection.Open();
        sqlDataMaster = new SqlDataAdapter(qryOrd, sqlConnection);
        sqlDataDet = new SqlDataAdapter(qryOrdDet, sqlConnection);

        //SET MASTER INSERT/UPDATES
        command = new SqlCommand("INSERT INTO Orders ( CustomerID, OrderDate, ShippedDate) VALUES (@CustID, @OrdDt, @ShipDt) SELECT SCOPE_IDENTITY();");

        command.Parameters.Add("@OrdID", SqlDbType.NVarChar, 15);
        command.Parameters.Add("@CustID", SqlDbType.VarChar, 15);
        command.Parameters["@CustID"].Value = cmbCust.SelectedText;

        command.Parameters.Add("@OrdDt", SqlDbType.DateTime);
        command.Parameters["@OrdDt"].Value = dtOrdDt.Text;

        command.Parameters.Add("@ShipDt", SqlDbType.DateTime);
        command.Parameters["@ShipDt"].Value =dtShipDt.Text;

        sqlDataMaster.InsertCommand = command;
        //string id = command.ExecuteScalar().ToString();

        command = new SqlCommand("UPDATE Orders SET CustomerID = @CustID, OrderDate = @OrdDt, ShippedDate = @ShipDt WHERE OrderID = @OrdID");

        command.Parameters.Add("@OrdID", SqlDbType.NVarChar, 15, "OrderID").Value = txtOrdID.Text; 
        command.Parameters.Add("@CustID", SqlDbType.VarChar, 15, "CustomerID").Value = cmbCust.Text;
        command.Parameters.Add("@OrdDt", SqlDbType.DateTime).Value = dtOrdDt.Text;
        command.Parameters.Add("@ShipDt", SqlDbType.DateTime).Value = dtShipDt.Text;
        sqlDataMaster.UpdateCommand = command;

        //SET DETAILS INSERT/UPDATES
        commandDet = new SqlCommand("INSERT INTO OrderDetails (ProductID, UnitPrice, Quantity) VALUES (@PrdID, @Up,@Qty)");

        //commandDet.Parameters.Add("@OrdID", SqlDbType.NVarChar, 15, "OrderID").Value = txtOrdID.Text; ;  
        commandDet.Parameters.Add("@PrdId", SqlDbType.NVarChar, 5, "ProductID");
        commandDet.Parameters.Add("@Up", SqlDbType.VarChar, 50, "UnitPrice");
        commandDet.Parameters.Add("@Qty", SqlDbType.VarChar, 20, "Quantity");
        sqlDataDet.InsertCommand = commandDet;

        commandDet = new SqlCommand("UPDATE OrderDetails SET ProductID = @PrdID, UnitPrice = @Up, Quantity = @Qty WHERE OrderID = @OrdID");
        commandDet.Parameters.Add("@OrdID", SqlDbType.NVarChar, 15, "OrderID").Value = txtOrdID.Text; ;  
        commandDet.Parameters.Add("@PrdId", SqlDbType.NVarChar, 5, "ProductID");
        commandDet.Parameters.Add("@Up", SqlDbType.VarChar, 50, "UnitPrice");
        commandDet.Parameters.Add("@Qty", SqlDbType.VarChar, 20, "Quantity");
        sqlDataDet.UpdateCommand = commandDet;

        sqlComBldMaster = new SqlCommandBuilder(sqlDataMaster);
        sqlComBldDet = new SqlCommandBuilder(sqlDataDet);

        dt = new DataTable();
        dtDet = new DataTable();

        dt.Clear();
        dtDet.Clear();

        sqlDataMaster.FillSchema(dt, SchemaType.Source);
        sqlDataDet.FillSchema(dtDet, SchemaType.Source);

        dtDet.Columns["OrderID"].AutoIncrement = true;
        dtDet.Columns["OrderID"].AutoIncrementSeed = -1;
        dtDet.Columns["OrderID"].AutoIncrementStep = -1;
        ds = new DataSet();
        ds.Tables.Add(dt);
        ds.Tables.Add(dtDet);
        ds.EnforceConstraints = false;

        DataRelation rel = new DataRelation("OrdersRel", ds.Tables["Orders"].Columns["OrderID"], ds.Tables["OrderDetails"].Columns["OrderID"]);
        ds.Relations.Add(rel);

        bs = new BindingSource();
        bsDet = new BindingSource();

        bs.DataSource = ds;
        bs.DataMember = "Orders";

        bsDet.DataSource = ds;
        bsDet.DataMember = "OrderDetails";

        dgInvDet.AutoGenerateColumns = false;

        dgInvDet.Columns["ProductID"].DataPropertyName = "ProductID";
        ProductID.DataSource = dm.GetData("Select * from Products order by ProductName");
        ProductID.DisplayMember = "ProductName";
        ProductID.ValueMember = "ProductID";
        dgInvDet.Columns["UnitPrice"].DataPropertyName = "UnitPrice";
        dgInvDet.Columns["Quantity"].DataPropertyName = "Quantity";   

        dgInvDet.DataSource = bsDet;
    }

public void SetComb()
{
        cmbCust.DataSource = dm.GetData("Select * from Customers order by CompanyName");
        cmbCust.DisplayMember = "CompanyName";
        cmbCust.ValueMember = "CustomerId";
        cmbCust.Text = "";
}

Dm.GetData is the data access class method created for the purpose of just retrieving rows...
And in the Save button click event:

 private void btnSave_Click(object sender, EventArgs e)
 {
     dt.EndInit();

     rec = sqlDataMaster.Update(ds.Tables[0]);
     rec += sqlDataDet.Update(ds.Tables[1]);
     //recDet = sqlDataDet.Update(dt);

     ds.AcceptChanges();            

     MessageBox.Show(rec + " record(s) applied...." );

     ds.EnforceConstraints = true;
}

What I need is to save the data to SQL Server in respective table (Orders and OrderDetails) which my code can't seem to do. It shows an error that foreign key cannot be null... because OrderDetails table also needs OrderID which is foreign key, and I am unable to understand how can I get the OrderID, as it is auto-generated after data is inserted into database.

Please help me on this problem to save the data in database with this foreign key issue...

Any help will be much appreciated.

Thanks

Ahmed

[BhuvanRam]

IF the orderid is AutoGenerated Column, afer insert get the value by calling MAX Function. Or use Stored Procedure Out Parameters (But this may completely change your code).

Look into these lines clearly

        command.Parameters.Add("@OrdID", SqlDbType.NVarChar, 15);

        **Why are using the above Line?** And you are not ppassing any value to this, so whats the use of passing Order ID?

        command.Parameters.Add("@CustID", SqlDbType.VarChar, 15);
        command.Parameters["@CustID"].Value = cmbCust.SelectedText;
        command.Parameters.Add("@OrdDt", SqlDbType.DateTime);
        command.Parameters["@OrdDt"].Value = dtOrdDt.Text;
        command.Parameters.Add("@ShipDt", SqlDbType.DateTime);
        command.Parameters["@ShipDt"].Value =dtShipDt.Text;

        sqlDataMaster.InsertCommand = command;

[ahmed_one]

Dear Sir,

Thank you very much for your reply, @OrdID in Parameters added because I need some way to get the generated ID and then pass it to OrderDetails foreinKey OrderID...but i couldn't find any solution for this...

If there is a better way, can you please guide me how to do it? even with StoredProc or any other way...

Your help and guidance for a newbie is much appreciated...

Thanks again

Ahmed