Shopping Cart Example code

Default.aspx

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeFile="Default.aspx.cs" Inherits="_Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <script type="text/javascript">
        function GetAmount()
        {
            var qty = document.getElementById('<%= txtQuantity.ClientID %>').value;
            var Price = document.getElementById('<%= txtPrice.ClientID %>').value;
            var Amount = (qty * Price);
            document.getElementById('<%= txtAmount.ClientID %>').value = Amount;
        }
    </script>
    <div>
        <asp:Label ID="lblMsg" runat="server"></asp:Label>
        <div>
            <div>
                Bill No:
            </div>
            <div>
                <asp:TextBox ID="txtBillNo" runat="server"></asp:TextBox>
                <asp:RequiredFieldValidator ID="rfvBillNo" runat="server" ValidationGroup="Customer"
                    ControlToValidate="txtBillNo" ErrorMessage="<b>please enter bill no</b>">
                </asp:RequiredFieldValidator>
            </div>
            <div>
                Customer Name:
            </div>
            <div>
                <asp:TextBox ID="txtCustomerName" runat="server"></asp:TextBox>
                <asp:RequiredFieldValidator ID="rfvCustomerName" runat="server" ValidationGroup="Customer"
                    ControlToValidate="txtCustomerName" ErrorMessage="<b>please enter CustomerName</b>">
                </asp:RequiredFieldValidator>
            </div>
            <div>
                Address:
            </div>
            <div>
                <asp:TextBox ID="txtAddress" runat="server"></asp:TextBox>
                <asp:RequiredFieldValidator ID="rfvAddress" runat="server" ValidationGroup="Customer"
                    ControlToValidate="txtAddress" ErrorMessage="<b>please enter Address</b>">
                </asp:RequiredFieldValidator>
            </div>
            <div>
                Gender:
            </div>
            <div>
                <asp:RadioButtonList ID="rblGender" runat="server">
                    <asp:ListItem Value="Male">Male</asp:ListItem>
                    <asp:ListItem Value="Female">Female</asp:ListItem>
                </asp:RadioButtonList>
            </div>
        </div>
        <div style="border: 1px solid gray; height: 200px; padding: 5px">
            <div style="width: 155px; float: left;">
                <div>
                    Product Name:
                </div>
                <div>
                    <asp:TextBox ID="txtProductName" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="rfvProductName" runat="server" ValidationGroup="Product"
                        ControlToValidate="txtProductName" ErrorMessage="<b>please enter product</b>">
                    </asp:RequiredFieldValidator>
                </div>
            </div>
            <div style="width: 155px; float: left;">
                <div>
                    Quantity:
                </div>
                <div>
                    <asp:TextBox ID="txtQuantity" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="rfvQuantity" runat="server" ValidationGroup="Product"
                        ControlToValidate="txtQuantity" ErrorMessage="<b>please enter Quantity</b>">
                    </asp:RequiredFieldValidator>
                </div>
            </div>
            <div style="width: 155px; float: left;">
                <div>
                    Price:
                </div>
                <div>
                    <asp:TextBox ID="txtPrice" runat="server" onblur = "GetAmount()"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="rfvPrice" runat="server" ValidationGroup="Product"
                        ControlToValidate="txtPrice" ErrorMessage="<b>please enter Price</b>">
                    </asp:RequiredFieldValidator>
                </div>
            </div>
            <div style="width: 155px; float: left;">
                <div>
                    Amount:
                </div>
                <div>
                    <asp:TextBox ID="txtAmount" runat="server"></asp:TextBox>
                </div>
            </div>
            <div style="margin: 15px;">
                <asp:Button ID="btnAdd" runat="server" ValidationGroup="Product" Text="Add" OnClick="btnAdd_Click" />
                <asp:Button ID="btnClear" runat="server" Text="Clear" OnClick="btnClear_Click" />
            </div>
            <asp:GridView ID="GVProduct" runat="server" OnRowCancelingEdit="GVProduct_RowCancelingEdit"
                OnRowDeleting="GVProduct_RowDeleting" OnRowEditing="GVProduct_RowEditing" >
                <Columns>
                    <asp:CommandField ButtonType="Button" ShowEditButton="true" />
                    <asp:CommandField ButtonType="Button" ShowDeleteButton="true" />
                </Columns>
            </asp:GridView>
        </div>
    </div>
    <div style="padding: 5px">
        <asp:Button ID="btnSave" runat="server" ValidationGroup="Customer" Text="Save" OnClick="btnSave_Click" />
        <asp:Button ID="btnCancel" runat="server" Text="Cancel" />
    </div>
</asp:Content>

Default.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;
using System.Text;

public partial class _Default : System.Web.UI.Page
{
    SqlConnection Conn = new SqlConnection();
    protected void Page_Load(object sender, EventArgs e)
    {
        CreateConnection();
    }

    public void CreateConnection()
    {
        Conn.ConnectionString = ConfigurationManager.ConnectionStrings["ConnString"].ToString();
    }
    protected void btnAdd_Click(object sender, EventArgs e)
    {
        DataTable dt = null;
        if (ViewState["dtProduct"] != null)
            dt = (DataTable)ViewState["dtProduct"];
        else
        {
            dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[4] { new DataColumn("Product", typeof(string)),
                            new DataColumn("Quantity", typeof(double)),
                            new DataColumn("Price",typeof(double)),
                            new DataColumn("Amount",typeof(double))});
        }

        if (btnAdd.Text == "Add")
        {
            dt.Rows.Add(txtProductName.Text, txtQuantity.Text, txtPrice.Text, txtAmount.Text);
        }
        else
        {
            int i = Convert.ToInt32(ViewState["Index"]);
            dt.Rows[i]["Product"] = txtProductName.Text;
            dt.Rows[i]["Quantity"] = txtQuantity.Text;
            dt.Rows[i]["Price"] = txtPrice.Text;
            dt.Rows[i]["Amount"] = txtAmount.Text;
        }
        GVProduct.EditIndex = -1;
        GVProduct.DataSource = dt;
        GVProduct.DataBind();
        ViewState["dtProduct"] = dt;
        ViewState["Index"] = null;
        btnAdd.Text = "Add";
        GVProduct.Enabled = true;
        ClearProduct();
    }

    public void ClearProduct()
    {
        txtProductName.Text = "";
        txtQuantity.Text = "";
        txtPrice.Text = "";
        txtAmount.Text = "";
    }

    public void Clear()
    {
        txtBillNo.Text = "";
        txtCustomerName.Text = "";
        txtAddress.Text = "";
        txtProductName.Text = "";
        txtQuantity.Text = "";
        txtPrice.Text = "";
        txtAmount.Text = "";
        ViewState["dtProduct"] = null;
    }
    protected void btnClear_Click(object sender, EventArgs e)
    {
        ClearProduct();
    }
    protected void btnSave_Click(object sender, EventArgs e)
    {
        if (ViewState["dtProduct"] != null)
        {
            CreateConnection();

            SqlCommand cmd = null;
            object obj = null;

            cmd = Conn.CreateCommand();

            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "Insert into Customerdetail(BillNo,CustomerName,Address,Gender) values (" + txtBillNo.Text + "," + "'" + txtCustomerName.Text + "'" + "," + "'" + txtAddress.Text + "'" + "," + "'" + (rblGender.SelectedItem.Text == "Male" ? "Male" : "Female") + "'" + ");SELECT SCOPE_IDENTITY()";

            try
            {
                Conn.Open();
                //obj = cmd.ExecuteScalar();
                int c_id = Convert.ToInt32(cmd.ExecuteScalar());

                if (c_id > 0)
                {
                    InsertProduct(c_id);
                    lblMsg.Text = "Insert Successfull";
                }
                else
                    lblMsg.Text = "Customer insert fail";
                Clear();
                ClearProduct();
                ViewState["dtProduct"] = null;
                GVProduct.DataSource = null;
                GVProduct.DataBind();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                cmd.Dispose();
                cmd = null;
                Conn.Close();
            }
        }
        else
        {
            lblMsg.Text = "Please Enter Product details";
        }
    }

    public void InsertProduct(int CustomerId)
    {
        DataTable dt = (DataTable)ViewState["dtProduct"];
        StringBuilder sbSql = new StringBuilder();

        sbSql.Append(@"INSERT INTO ProductDetails(CustomerId,ProductName,Quantity,Price,Amount) VALUES");
        // Response.Write("Outer Looop" + i.ToString() + "<br/><br/>");
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            //  Response.Write("Inner Looop" + j.ToString() + "<br/>");
            string values = string.Format("({0},{1},{2},{3},{4}),",
                new string[] { Convert.ToString(CustomerId), "'" + dt.Rows[i]["Product"] + "'", "'" + dt.Rows[i]["Quantity"] + "'", "'" + dt.Rows[i]["Price"] + "'", "'" + dt.Rows[i]["Amount"] + "'" });
            sbSql.Append(values);
        }
        string sql = sbSql.ToString();
        sql = sql.TrimEnd(',');
        //SqlConnection con = new SqlConnection();
        //Conn.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = Conn;
        cmd.CommandText = sql;
        cmd.CommandType = System.Data.CommandType.Text;
        cmd.ExecuteNonQuery();
        sbSql.Clear();
    }

    protected void GVProduct_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GVProduct.DataSource = (DataTable)ViewState["dtProduct"];
        GVProduct.DataBind();
        btnAdd.Text = "Update";
        txtProductName.Text = GVProduct.Rows[e.NewEditIndex].Cells[2].Text;
        txtQuantity.Text = GVProduct.Rows[e.NewEditIndex].Cells[3].Text;
        txtPrice.Text = GVProduct.Rows[e.NewEditIndex].Cells[4].Text;
        txtAmount.Text = GVProduct.Rows[e.NewEditIndex].Cells[5].Text;
        GVProduct.Enabled = false;
        ViewState["Index"] = e.NewEditIndex;
        GVProduct.EditIndex = -1;
    }
    protected void GVProduct_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GVProduct.EditIndex = -1;
        GVProduct.DataSource = ViewState["dtProduct"];
        GVProduct.DataBind();
    }
    protected void GVProduct_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        DataTable dt = null;
        if (ViewState["dtProduct"] != null)
            dt = (DataTable)ViewState["dtProduct"];
        dt.Rows.RemoveAt(e.RowIndex);
        ViewState["dtProduct"] = dt;
        GVProduct.DataSource = dt;
        GVProduct.DataBind();
    }
}