As reviewed above, before using a regular class to manipulate a database, you should first create a class. To do this, you must know the structure of the table that will be represented by the class. This means that you should be familiar with the tables in the data set object. After creating the class, to get the values from a table, you can declare a variable from a collection-based class. Then, you can use the properties and methods of the collection class.

1. In the Solution Explorer, right-click CollegeParkAutoParts2 -> Add -> Class...
2. Set the name to AutoPart and press Enter
3. Create a class as follows:
   

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Threading.Tasks;
   
   namespace CollegeParkAutoParts2
   {
       public class AutoPart
       {
           public int PartNumber   { get; set; }
   	public int CarYear      { get; set; }
   	public string Make      { get; set; }
   	public string Model     { get; set; }
   	public string Category  { get; set; }
   	public string PartName  { get; set; }
   	public double UnitPrice { get; set; }
       }
   }

4. Display the Part Editor form and double-click an empty area of its body
5. Implement the event as follows:
   

   internal void ResetPartEditor()
   {
       cbxYears.Items.Clear();
       cbxMakes.Items.Clear();
       cbxModels.Items.Clear();
       cbxCategories.Items.Clear();
       cbxYears.Text = "";
       cbxMakes.Text = "";
       cbxModels.Text = "";
       cbxCategories.Text = "";
       txtPartName.Text = "";
       txtUnitPrice.Text = "0.00";
   
       Random rndNumber = new Random();
   
       txtPartNumber.Text = rndNumber.Next(100001, 999999).ToString();
   
       // Put the years in the top combo box
       // Start with next year down to 1960
       for (int i = DateTime.Today.Year + 1; i >= 1960; i--)
           cbxYears.Items.Add(i.ToString());
    
       // Prepare a data set object for the parts
       DataSet dsParts = new DataSet("PartsSet");
   
       // Establish a connection to the database
       using (SqlConnection scCollegeParkAutoParts =
           new SqlConnection("Data Source=(local);" +
                             "Database=CollegeParkAutoParts1;" +
                             "Integrated Security=SSPI;"))
       {
           // Create a command that will select the parts
           SqlCommand cmdParts =
               new SqlCommand("SELECT PartNumber, " +
                              "       CarYear, " +
                              "       Make, " +
                              "       Model, " +
                              "       Category, " +
                              "       PartName, " +
                              "       UnitPrice " +
                              "FROM Inventory.AutoParts;", scCollegeParkAutoParts);
           cmdParts.CommandType = CommandType.Text;
           // Open the connection
           scCollegeParkAutoParts.Open();
   
           // Create a data adapter that will get the values from the table
           SqlDataAdapter sdaParts = new SqlDataAdapter(cmdParts);
           // Store those values in the data set
           sdaParts.Fill(dsParts);
   
           // Create an auto part object
           AutoPart StoreItem = null;
           // Create an empty list of auto parts
           List<AutoPart> lstAutoParts = new List<AutoPart>();
   
           // Check each record from the (only) table in the data set
           foreach (DataRow row in dsParts.Tables[0].Rows)
           {
               // Use the auto part object ...
               StoreItem = new AutoPart();
               // ... to create a record object
               StoreItem.PartNumber = int.Parse(row[0].ToString());
               StoreItem.CarYear = int.Parse(row[1].ToString());
               StoreItem.Make = row[2].ToString();
               StoreItem.Model = row[3].ToString();
               StoreItem.Category = row[4].ToString();
               StoreItem.PartName = row[5].ToString();
               StoreItem.UnitPrice = double.Parse(row[6].ToString());
               // Once the record is ready, store it in the collection variable
               lstAutoParts.Add(StoreItem);
           }
   
           // To avoid duplicate values in the combo boxes, 
           // we will use collection classes
           List<string> lstMakes = new List<string>();
           List<string> lstCategories = new List<string>();
   
           // Check the list of makes
           foreach (AutoPart part in lstAutoParts)
           {
               // If the list doesn't yet contain the make, add it
               if (!lstMakes.Contains(part.Make))
                   lstMakes.Add(part.Make);
           }
   
           // Once we have the list of makes, 
           // put them in the Make combo box
           foreach (string strMake in lstMakes)
               cbxMakes.Items.Add(strMake);
   
           foreach (AutoPart part in lstAutoParts)
           {
               if (!lstCategories.Contains(part.Category))
                   lstCategories.Add(part.Category);
           }
   
           foreach (string strCategory in lstCategories)
               cbxCategories.Items.Add(strCategory);
       }
   }
   
   private void PartEditor_Load(object sender, EventArgs e)
   {
       ResetPartEditor();
   }

6. Call the ResetPartEditor() method before the closing curly bracket of the Click event of the Submit button:
   

   private void btnSubmit_Click(object sender, EventArgs e)
   {
       . . . No Change            
                
       ResetPartEditor();
   }

7. Return to the Part Editor form and double-click the Year combo box
8. Implement the event as follows:
   

   private void cbxYears_SelectedIndexChanged(object sender, EventArgs e)
   {
       // If the user was working on a previous part, cancel it
       cbxModels.Items.Clear();
   }

9. Return to the Part Editor form and double-click the Make combo box
10. Implement its event as follows:
    

    private void cbxMakes_SelectedIndexChanged(object sender, EventArgs e)
    {
        // Create a data set of parts
        DataSet dsParts = new DataSet("PartsSet");
    
        // Establish a connection to the database
        using (SqlConnection scCollegeParkAutoParts =
            new SqlConnection("Data Source=(local);" +
                              "Database=CollegeParkAutoParts1;" +
                              "Integrated Security=SSPI;"))
        {
            // Create a command that will select the parts
            SqlCommand cmdParts =
            new SqlCommand("SELECT PartNumber, " +
                           "       CarYear, " +
                           "       Make, " +
                           "       Model, " +
                           "       Category, " +
                           "       PartName, " +
                           "       UnitPrice " +
                           "FROM Inventory.AutoParts;", scCollegeParkAutoParts);
            // Open the connection
            scCollegeParkAutoParts.Open();
    
            // Create a data adapter that will get 
            // the record from the command
            SqlDataAdapter sdaParts = new SqlDataAdapter(cmdParts);
    
            // Store those records in the data set
            sdaParts.Fill(dsParts);
    
            // Create an empty object that can receive one record
            AutoPart StoreItem = null;
            // Create an empty list that can receive a list of records
            List<AutoPart> lstAutoParts = new List<AutoPart>();
    
            // Check each record
            foreach (DataRow row in dsParts.Tables[0].Rows)
            {
                // Get the values of the current record
                StoreItem = new AutoPart();
                // Store the values in the object
                StoreItem.PartNumber = int.Parse(row[0].ToString());
                StoreItem.CarYear = int.Parse(row[1].ToString());
                StoreItem.Make = row[2].ToString();
                StoreItem.Model = row[3].ToString();
                StoreItem.Category = row[4].ToString();
                StoreItem.PartName = row[5].ToString();
                StoreItem.UnitPrice = double.Parse(row[6].ToString());
                // Once the record is ready, store it in the collection
                lstAutoParts.Add(StoreItem);
            }
    
            // This will hold the list of parts
            List<string> lstModels = new List<string>();
    
            foreach (AutoPart part in lstAutoParts)
            {
                if ((part.CarYear == int.Parse(cbxYears.Text)) &&
                    (part.Make == cbxMakes.Text))
                {
                    if (!lstModels.Contains(part.Model))
                        lstModels.Add(part.Model);
                }
            }
    
            foreach (string strModel in lstModels)
                cbxModels.Items.Add(strModel);
        }
    }

11. Access the College Park Auto-Parts form and double-click anunoccupied area of its body
12. Implement the event as follows:
    

    internal void ShowAutoParts()
    {
        tvwAutoParts.Nodes.Clear();
        TreeNode nodRoot =
        tvwAutoParts.Nodes.Add("College Park Auto-Parts",
                               "College Park Auto-Parts", 0, 1);
        // Show the years nodes
        for (int years = DateTime.Today.Year + 1; years >= 1960; years--)
            nodRoot.Nodes.Add(years.ToString(), years.ToString(), 2, 3);
    
        tvwAutoParts.SelectedNode = nodRoot;
        // Expand the root node
        tvwAutoParts.ExpandAll();
    
        // Create an empty data set
        DataSet dsParts = new DataSet("PartsSet");
    
        // Create a connection to the database
        using (SqlConnection scCollegeParkAutoParts =
            new SqlConnection("Data Source=(local);" +
                              "Database=CollegeParkAutoParts1;" +
                              "Integrated Security=SSPI;"))
        {
            // Use a command to specify what action we want to take
            SqlCommand cmdParts =
            new SqlCommand("SELECT PartNumber, " +
                           "       CarYear, " +
                           "       Make, " +
                           "       Model, " +
                           "       Category, " +
                           "       PartName, " +
                           "       UnitPrice " +
                           "FROM Inventory.AutoParts;", scCollegeParkAutoParts);
            // Open the connection
            scCollegeParkAutoParts.Open();
    
            // Use a data adapter to retrieve the values from the command
            SqlDataAdapter sdaParts = new SqlDataAdapter(cmdParts);
            // Fill the data set with the values from the data adapater
            sdaParts.Fill(dsParts);
    
            // Prepare a variable from the class we will use
            AutoPart StoreItem = null;
            // Create a collection
            List<AutoPart> lstAutoParts = new List<AutoPart>();
    
            // Check each record from the table from the data set
            foreach (DataRow row in dsParts.Tables[0].Rows)
            {
                // Identify each record as a value of our class
                StoreItem = new AutoPart();
                // Get the values of the record and put them in the class
                StoreItem.PartNumber = int.Parse(row[0].ToString());
                StoreItem.CarYear = int.Parse(row[1].ToString());
                StoreItem.Make = row[2].ToString();
                StoreItem.Model = row[3].ToString();
                StoreItem.Category = row[4].ToString();
                StoreItem.PartName = row[5].ToString();
                StoreItem.UnitPrice = double.Parse(row[6].ToString());
                // Store the record in the collection
                lstAutoParts.Add(StoreItem);
            }
    
            // Now that we have the records, 
            // we can use them as a normal collection
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                List<string> lstMakes = new List<string>();
    
                foreach (AutoPart part in lstAutoParts)
                {
                    if (nodYear.Text == part.CarYear.ToString())
                    {
                        if (!lstMakes.Contains(part.Make))
                            lstMakes.Add(part.Make);
                    }
                }
    
                foreach (string strMake in lstMakes)
                    nodYear.Nodes.Add(strMake, strMake, 4, 5);
            }
    
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                foreach (TreeNode nodMake in nodYear.Nodes)
                {
                    List<string> lstModels = new List<string>();
    
                    foreach (AutoPart part in lstAutoParts)
                    {
                        if ((nodYear.Text == part.CarYear.ToString()) &&
                            (nodMake.Text == part.Make))
                        {
                            if (!lstModels.Contains(part.Model))
                                lstModels.Add(part.Model);
                        }
                    }
    
                    foreach (string strModel in lstModels)
                        nodMake.Nodes.Add(strModel, strModel, 6, 7);
                }
            }
    
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                foreach (TreeNode nodMake in nodYear.Nodes)
                {
                    foreach (TreeNode nodModel in nodMake.Nodes)
                    {
                        List<string> lstCategories = new List<string>();
    
                        foreach (AutoPart part in lstAutoParts)
                        {
                            if ((nodYear.Text == part.CarYear.ToString()) &&
                                (nodMake.Text == part.Make) &&
                                (nodModel.Text == part.Model))
                            {
                                if (!lstCategories.Contains(part.Category))
                                    lstCategories.Add(part.Category);
                            }
                        }
    
                        foreach (string strCategory in lstCategories)
                            nodModel.Nodes.Add(strCategory, strCategory, 8, 9);
                    }
                }
            }
        }
    }
    
    private void CollegeParkAutoParts_Load(object sender, EventArgs e)
    {
        ShowAutoParts();
    }	
    

13. Return to the College Park Auto-Parts form and double-click the New Auto Part button
14. Implement the event as follows:
    

    private void btnNewAutoPart_Click(object sender, EventArgs e)
    {
        PartEditor editor = new PartEditor();
    
        if (editor.ShowDialog() == DialogResult.Cancel)
            ShowAutoParts();
    }

15. Return to the  College Park Auto-Parts form and click the tree view
16. In the Properties window, click the Events button and, in the Events section, double-click NodeMouseClick
17. Implement the event as follows:
    

    private void tvwAutoParts_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
    {
        TreeNode nodClicked = e.Node;
    
        if (nodClicked.Level == 4)
            lvwAutoParts.Items.Clear();
    
        DataSet dsParts = new DataSet("PartsSet");
    
        using (SqlConnection scCollegeParkAutoParts =
            new SqlConnection("Data Source=(local);" +
                              "Database=CollegeParkAutoParts1;" +
                              "Integrated Security=SSPI;"))
        {
            SqlCommand cmdParts =
            new SqlCommand("SELECT PartNumber, " +
                           "       CarYear, " +
                           "       Make, " +
                           "       Model, " +
                           "       Category, " +
                           "       PartName, " +
                           "       UnitPrice " +
                           "FROM Inventory.AutoParts;", scCollegeParkAutoParts);
            scCollegeParkAutoParts.Open();
    
            SqlDataAdapter sdaParts = new SqlDataAdapter(cmdParts);
            sdaParts.Fill(dsParts);
    
            AutoPart StoreItem = null;
            List<AutoPart> lstAutoParts = new List<AutoPart>();
    
            foreach (DataRow row in dsParts.Tables[0].Rows)
            {
                StoreItem = new AutoPart();
                StoreItem.PartNumber = int.Parse(row[0].ToString());
                StoreItem.CarYear = int.Parse(row[1].ToString());
                StoreItem.Make = row[2].ToString();
                StoreItem.Model = row[3].ToString();
                StoreItem.Category = row[4].ToString();
                StoreItem.PartName = row[5].ToString();
                StoreItem.UnitPrice = double.Parse(row[6].ToString());
                lstAutoParts.Add(StoreItem);
            }
    
            try
            {
                foreach (AutoPart part in lstAutoParts)
                {
                    if ((part.Category == nodClicked.Text) &&
                        (part.Model == nodClicked.Parent.Text) &&
                        (part.Make == nodClicked.Parent.Parent.Text) &&
                    (part.CarYear.ToString() == nodClicked.Parent.Parent.Parent.Text))
                    {
                        ListViewItem lviAutoPart =
                            new ListViewItem(part.PartNumber.ToString());
    
                        lviAutoPart.SubItems.Add(part.PartName);
                        lviAutoPart.SubItems.Add(part.UnitPrice.ToString("F"));
                        lvwAutoParts.Items.Add(lviAutoPart);
                    }
                }
            }
            catch (NullReferenceException)
            {
            }
        }
    }

18. Return to the College Park Auto-Parts form and double-click the Add/Select button
19. Implement the event as follows:
    

    private void btnAdd_Click(object sender, EventArgs e)
    {
        if (txtPartNumber.Text.Length == 0)
        {
            MessageBox.Show("There is no part to be added to the order.",
                            "College Park Auto-Parts",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            return;
        }
    
        DataSet dsParts = new DataSet("PartsSet");
    
        using (SqlConnection scCollegeParkAutoParts =
              new SqlConnection("Data Source=(local);" +
                                "Database=CollegeParkAutoParts1;" +
                                "Integrated Security=SSPI;"))
        {
            SqlCommand cmdParts =
         new SqlCommand("SELECT * FROM Inventory.AutoParts;", scCollegeParkAutoParts);
            scCollegeParkAutoParts.Open();
    
            SqlDataAdapter sdaParts = new SqlDataAdapter(cmdParts);
            sdaParts.Fill(dsParts);
    
            AutoPart StoreItem = null;
            List<AutoPart> lstAutoParts = new List<AutoPart>();
    
            foreach (DataRow row in dsParts.Tables[0].Rows)
            {
                StoreItem = new AutoPart();
                StoreItem.PartNumber = int.Parse(row[0].ToString());
                StoreItem.CarYear = int.Parse(row[1].ToString());
                StoreItem.Make = row[2].ToString();
                StoreItem.Model = row[3].ToString();
                StoreItem.Category = row[4].ToString();
                StoreItem.PartName = row[5].ToString();
                StoreItem.UnitPrice = double.Parse(row[6].ToString());
                lstAutoParts.Add(StoreItem);
            }
    
            foreach (AutoPart part in lstAutoParts)
            {
                if (part.PartNumber == int.Parse(txtPartNumber.Text))
                {
                    ListViewItem lviSelectedPart =
                        new ListViewItem(part.PartNumber.ToString());
    
                    lviSelectedPart.SubItems.Add(part.PartName);
                    lviSelectedPart.SubItems.Add(part.UnitPrice.ToString());
                    lviSelectedPart.SubItems.Add(txtQuantity.Text);
                    lviSelectedPart.SubItems.Add(txtSubTotal.Text);
                    lvwSelectedParts.Items.Add(lviSelectedPart);
                }
            }
    
            CalculateOrder();
        }
    }

20. Return to the College Park Auto-Parts form and double-click the Save Customer Order button
21. Implement the event as follows:
    

    private void btnSave_Click(object sender, EventArgs e)
    {
        if (lvwSelectedParts.Items.Count == 0)
            return;
        else
        {
            using (SqlConnection scAltairRealtors =
                new SqlConnection("Data Source=(local);" +
                           "Database='CollegeParkAutoParts1';" +
                           "Integrated Security='SSPI';"))
            {
                SqlCommand cmdProperty =
                    new SqlCommand("INSERT INTO Transactions.CustomersOrders(ReceiptNumber, " +
                                   "PartsTotal, TaxRate, TaxAmount, OrderTotal) VALUES(" + txtSave.Text + ", " +
                                   txtPartsTotal.Text + ", " + txtTaxRate.Text + ", " +
                                   txtTaxAmount.Text + ", " + txtOrderTotal.Text + ");",
                                   scAltairRealtors);
    
                scAltairRealtors.Open();
                cmdProperty.ExecuteNonQuery();
            }
    
            // Check each selected part and get it ready to add to the table
            // Each selected part of this order will have a common receipt #
            for (int i = 0; i < lvwSelectedParts.Items.Count; i++)
            {
                using (SqlConnection cnnCustomerOrder =
                  new SqlConnection("Data Source=(local);" +
                                    "Database=CollegeParkAutoParts1;" +
                                    "Integrated Security=SSPI;"))
                {
                    SqlCommand cmdCustomerOrder =
                        new SqlCommand("INSERT INTO Transactions.PartsSold(ReceiptNumber, PartNumber, PartName, " +
                        "UnitPrice, Quantity, SubTotal) VALUES(" + txtSave.Text + ", N'" +
                        lvwSelectedParts.Items[i].Text + "', '" +
                        lvwSelectedParts.Items[i].SubItems[1].Text + "', '" +
                        lvwSelectedParts.Items[i].SubItems[2].Text + "', '" +
                        lvwSelectedParts.Items[i].SubItems[3].Text + "', '" +
                        lvwSelectedParts.Items[i].SubItems[4].Text + "'); ", cnnCustomerOrder);
                    cnnCustomerOrder.Open();
    
                    cmdCustomerOrder.ExecuteNonQuery();
                }
            }
    
            MessageBox.Show("The customer order has been saved.",
                            "College Park Auto-Parts",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
    
        CollegeParkAutoParts_Load(sender, e);
    }

22. Change the Load event as follows:

    private void SetReceiptNumber()
    {
        int iReceiptNumber = 0;
    
        using (SqlConnection scCustomersOrders =
           new SqlConnection(@"Data Source='CENTRAL\MSSQLSERVER2012';" +
                              "Database=CollegeParkAutoParts1;" +
                              "Integrated Security=SSPI;"))
        {
            SqlCommand cmdCustomersOrders =
                       new SqlCommand("SELECT ReceiptNumber " +
                             "FROM Transactions.CustomersOrders;", scCustomersOrders);
    
            scCustomersOrders.Open();
            SqlDataReader rdrCustomersOrders = cmdCustomersOrders.ExecuteReader();
    
            while (rdrCustomersOrders.Read())
                iReceiptNumber = int.Parse(rdrCustomersOrders[0].ToString());
        }
    
        txtSave.Text = (iReceiptNumber + 1).ToString();
    }
    
    private void CollegeParkAutoParts_Load(object sender, EventArgs e)
    {
        ShowAutoParts();
        SetReceiptNumber();
    
        lvwAutoParts.Items.Clear();
        txtPartNumber.Text = "";
        txtPartName.Text = "";
        txtUnitPrice.Text = "0.00";
        txtQuantity.Text = "0";
        txtSubTotal.Text = "0.00";
        lvwSelectedParts.Items.Clear();
        txtPartsTotal.Text = "0.00";
        txtTaxRate.Text = "5.75";
        txtTaxAmount.Text = "0.00";
        txtOrderTotal.Text = "0.00";
        txtOpen.Text = "";
    }

23. Return to the College Park Auto-Parts form and double-click the Open button
24. Implement the event as follows:
    

    private void btnOpen_Click(object sender, EventArgs e)
    {
        lvwSelectedParts.Items.Clear();
    
        if (string.IsNullOrEmpty(txtOpen.Text))
            return;
        else
        {
            using (SqlConnection cnnCustomerOrder =
                   new SqlConnection("Data Source=(local);" +
                                     "Database=CollegeParkAutoParts1;" +
                                     "Integrated Security=SSPI;"))
            {
                SqlCommand cmdCustomerOrder =
                    new SqlCommand("SELECT * FROM Transactions.PartsSold " +
                                   "WHERE ReceiptNumber = '" + txtOpen.Text + "';",
                                   cnnCustomerOrder);
                SqlDataAdapter sdaCustomerOrder =
                    new SqlDataAdapter(cmdCustomerOrder);
    
                cnnCustomerOrder.Open();
    
                DataSet dsCustomerOrder = new DataSet("PartsSoldSet");
                sdaCustomerOrder.Fill(dsCustomerOrder);
    
                for (int i = 0; i < dsCustomerOrder.Tables[0].Rows.Count; i++)
                {
                    DataRow rowOrder = dsCustomerOrder.Tables[0].Rows[i];
    
                    ListViewItem lviOrder =
                        new ListViewItem(rowOrder["PartNumber"].ToString());
                    lviOrder.SubItems.Add(rowOrder["PartName"].ToString());
                    lviOrder.SubItems.Add(rowOrder["UnitPrice"].ToString());
                    lviOrder.SubItems.Add(rowOrder["Quantity"].ToString());
                    lviOrder.SubItems.Add(rowOrder["SubTotal"].ToString());
                    lvwSelectedParts.Items.Add(lviOrder);
                }
            }
    
            using (SqlConnection cnnInvoice =
                   new SqlConnection("Data Source=(local);" +
                                     "Database=CollegeParkAutoParts1;" +
                                     "Integrated Security=SSPI;"))
            {
                string strInvoice = "SELECT ReceiptNumber, PartsTotal, TaxRate, " +
                                    "TaxAmount, OrderTotal " +
                                    "FROM Transactions.CustomersOrders " +
                                    "WHERE ReceiptNumber = " + txtOpen.Text + ";";
    
                SqlCommand cmdInvoice = new SqlCommand(strInvoice, cnnInvoice);
    
                cnnInvoice.Open();
                SqlDataReader rdrInvoice = cmdInvoice.ExecuteReader();
    
                while (rdrInvoice.Read())
                {
                    txtPartsTotal.Text = rdrInvoice[1].ToString();
                    txtTaxRate.Text = rdrInvoice[2].ToString();
                    txtTaxAmount.Text = rdrInvoice[3].ToString();
                    txtOrderTotal.Text = rdrInvoice[4].ToString();
                }
            }
        }
    }

25. Return to the College Park Auto-Parts form and double-click the New Customer button
26. Implement the event as follows:
    

    private void btnNewCustomerOrder_Click(object sender, EventArgs e)
    {
        ShowAutoParts();
        lvwAutoParts.Items.Clear();
        txtPartNumber.Text = "";
        txtPartName.Text = "";
        txtUnitPrice.Text = "0.00";
        txtQuantity.Text = "0";
        txtSubTotal.Text = "0.00";
        lvwSelectedParts.Items.Clear();
        txtPartsTotal.Text = "0.00";
        txtTaxRate.Text = "5.75";
        txtTaxAmount.Text = "0.00";
        txtOrderTotal.Text = "0.00";
        txtOpen.Text = "";
    }

27. Return to the College Park Auto-Parts form and double-click the Close button
28. Implement the event as follows:
    

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

29. Execute the application
30. Click the New Auto Part button and use the Part Editor to create a few parts
31. Create a few customers orders and save them
32. Close the forms and return to your programming environment
33. Execute the application again and open a previously saved order
34. Close the forms and return to your programming environment

1. Open the CollegeParkAutoParts3 database from this lesson
2. Add a context menu for the Available Parts list view with the items: Select, Edit..., and Delete
    
   
3. Configure the context menu so that
   1. If the user clicks Select, the behavior would be the same as if the user had double-clicked the item
   2. If the user clicks Edit..., the Part Editor dialog box would display with the part in it. The user can then edit any part (year, make, model, category, part name, or unit price) except the part number. Then the user can save the changed part
   3. If the user clicks Delete, a message box would warn the user and ask for confirmation with Yes/No answers. If the user clicks Yes, the part would be deleted from the AutoParts table
4. Configure the application so that the user can open an order, add new parts to it, or delete parts from it, then save the order
5. Extend the application so that the store can also sell items that are, or are not, car-related, such as books, t-shirts, cleaning items, maintenance items (steering oils, brake oils, etc), license plates, etc. Every item in the store should have an item number. The user can enter that item number in the Part # text box and press Tab or Enter. The corresponding item would then be retrieved from the database and displayed on the form. If there is no item with that number, a message box should let the user know