Retrieve (Fetch) data from StringBuilder and bind GridView using C# and VB.Net in ASP.Net

suhaas121 says:

string[] vendors = Session["vendor"].ToString().Split('\n');

Loop through the string array to get each row details.

Check this example. Now please take its reference and correct your code.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

Home

<asp:GridView ID="GridView1" runat="server">
    <Columns>
        <asp:TemplateField>
            <EditItemTemplate>
                <asp:CheckBox ID="CheckBox1" runat="server" />
            </EditItemTemplate>
            <ItemTemplate>
                <asp:CheckBox ID="CheckBox1" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<asp:Button ID="btnadd" OnClick="btnadd_Click" runat="server" Text="Add To Cart" />

Default

<asp:GridView runat="server" ID="GridView1"></asp:GridView>

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient

Code

C#

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protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] {
        new DataColumn("Id"), new DataColumn("Name"), new DataColumn("Country") });
        dt.Rows.Add(1, "John Hammond", "United States");
        dt.Rows.Add(2, "Mudassar Khan", "India");
        dt.Rows.Add(3, "Suzanne Mathews", "France");
        dt.Rows.Add(4, "Robert Schidner", "Russia");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

protected void btnadd_Click(object sender, EventArgs e)
{
    StringBuilder strb = new StringBuilder();
    for (int i = 0; i < GridView1.Rows.Count; i++)
    {
        GridViewRow row = GridView1.Rows[i];
        bool isChecked = ((CheckBox)row.FindControl("CheckBox1")).Checked;
        if (isChecked)
        {
            strb.Append(GridView1.Rows[i].Cells[1].Text).AppendLine();
        }
    }
    Session["vendor"] = strb.ToString().Trim();
    Response.Redirect("Default.aspx");
}

Default

protected void Page_Load(object sender, EventArgs e)
{
    if (Session["vendor"] != null)
    {
        string[] vendors = Session["vendor"].ToString().Split('\n');
        DataSet ds = new DataSet();
        foreach (string vendor in vendors)
        {
            var data = vendor.Trim();
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
            SqlCommand cmd = new SqlCommand("select FirstName+' '+LastName Name,Country from Employees where EmployeeID='" + data + "'", conn);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                if (ds.Tables.Count > 0)
                {
                    ds.Tables[0].Merge(dt);
                }
                else
                {
                    ds.Tables.Add(dt);
                }
            }
        }
        GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind();
    }
}

VB.Net

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Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.AddRange(New DataColumn(2) {
                        New DataColumn("Id"), New DataColumn("Name"), New DataColumn("Country")})
        dt.Rows.Add(1, "John Hammond", "United States")
        dt.Rows.Add(2, "Mudassar Khan", "India")
        dt.Rows.Add(3, "Suzanne Mathews", "France")
        dt.Rows.Add(4, "Robert Schidner", "Russia")
        GridView1.DataSource = dt
        GridView1.DataBind()
    End If
End Sub

Protected Sub btnadd_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim strb As StringBuilder = New StringBuilder()
    For i As Integer = 0 To GridView1.Rows.Count - 1
        Dim row As GridViewRow = GridView1.Rows(i)
        Dim isChecked As Boolean = (CType(row.FindControl("CheckBox1"), CheckBox)).Checked
        If isChecked Then
            strb.Append(GridView1.Rows(i).Cells(1).Text).AppendLine()
        End If
    Next

    Session("vendor") = strb.ToString().Trim()
    Response.Redirect("Default.aspx")
End Sub

Default

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Session("vendor") IsNot Nothing Then
        Dim vendors As String() = Session("vendor").ToString().Split(vbLf)
        Dim ds As DataSet = New DataSet()
        For Each vendor As String In vendors
            Dim data = vendor.Trim()
            Dim conn As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("connString").ConnectionString)
            Dim cmd As SqlCommand = New SqlCommand("select FirstName+' '+LastName Name,Country from Employees where EmployeeID='" & data & "'", conn)
            Dim da As SqlDataAdapter = New SqlDataAdapter(cmd)
            Dim dt As DataTable = New DataTable()
            da.Fill(dt)
            If dt.Rows.Count > 0 Then
                If ds.Tables.Count > 0 Then
                    ds.Tables(0).Merge(dt)
                Else
                    ds.Tables.Add(dt)
                End If
            End If
        Next

        GridView1.DataSource = ds.Tables(0)
        GridView1.DataBind()
    End If
End Sub

Screenshot