Populate TextBox inside ASP.Net Gridview based on another TextChanged using C# and VB.Net

Hi BugHunter,

Refer below sample.

HTML

<asp:GridView ID="GridAddSCode" runat="server" AutoGenerateColumns="False">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:TemplateField HeaderText="CustomerId">
            <ItemTemplate>
                <asp:TextBox ID="txtCustomerId" OnTextChanged="txtState_TextChanged" AutoPostBack="true"
                    runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Country">
            <ItemTemplate>
                <asp:TextBox ID="txtCountry" Enabled="false" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<br />
<asp:Button Text="Save" runat="server" OnClick="Save" />
<br />
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
    <Columns>
        <asp:BoundField DataField="CustomerId" HeaderText="Id" />
        <asp:BoundField DataField="Country" HeaderText="Country" />
    </Columns>
</asp:GridView>

Namespaces

C#

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

VB.Net

Imports System.Data
Imports System.Data.SqlClient

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Id");
        dt.Rows.Add(1);
        dt.Rows.Add(2);
        dt.Rows.Add(3);
        GridAddSCode.DataSource = dt;
        GridAddSCode.DataBind();
    }
}

protected void txtState_TextChanged(object sender, EventArgs e)
{
    GridViewRow clickedrow = ((TextBox)sender).NamingContainer as GridViewRow;
    TextBox txtCustomerId = (TextBox)clickedrow.FindControl("txtCustomerId");
    TextBox txtCountry = (TextBox)clickedrow.FindControl("txtCountry");
    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand(@"SELECT Country FROM Customers WHERE CustomerId = @CustomerId", con))
        {
            cmd.Parameters.AddWithValue("@CustomerId", txtCustomerId.Text.Trim());
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                DataTable dt = new DataTable();
                da.Fill(dt);
                txtCountry.Text = dt.Rows[0]["Country"].ToString();
            }
        }
    }
}

protected void Save(object sender, EventArgs e)
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString);
    SqlCommand cmd = null;
    for (int i = 0; i < GridAddSCode.Rows.Count; i++)
    {
        TextBox txtCustomerId = GridAddSCode.Rows[i].FindControl("txtCustomerId") as TextBox;
        TextBox txtCountry = GridAddSCode.Rows[i].FindControl("txtCountry") as TextBox;
        cmd = new SqlCommand(@"INSERT INTO CustomerTestDemo(Customerid, Country) VALUES(@Customerid, @Country)", con);
        cmd.Parameters.AddWithValue("@CustomerId", txtCustomerId.Text.Trim());
        cmd.Parameters.AddWithValue("@Country", txtCountry.Text.Trim());
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
    }

    cmd = new SqlCommand("SELECT CustomerId, Country FROM CustomerTestDemo", con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    da.Fill(dt);
    GridView1.DataSource = dt;
    GridView1.DataBind();
}

VB.Net

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.Add("Id")
        dt.Rows.Add(1)
        dt.Rows.Add(2)
        dt.Rows.Add(3)
        GridAddSCode.DataSource = dt
        GridAddSCode.DataBind()
    End If
End Sub

Protected Sub txtState_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
    Dim clickedrow As GridViewRow = TryCast((CType(sender, TextBox)).NamingContainer, GridViewRow)
    Dim txtCustomerId As TextBox = CType(clickedrow.FindControl("txtCustomerId"), TextBox)
    Dim txtCountry As TextBox = CType(clickedrow.FindControl("txtCountry"), TextBox)

    Using con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
        Using cmd As SqlCommand = New SqlCommand("SELECT Country FROM Customers WHERE CustomerId = @CustomerId", con)
            cmd.Parameters.AddWithValue("@CustomerId", txtCustomerId.Text.Trim())
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                Dim dt As DataTable = New DataTable()
                da.Fill(dt)
                txtCountry.Text = dt.Rows(0)("Country").ToString()
            End Using
        End Using
    End Using
End Sub

Protected Sub Save(ByVal sender As Object, ByVal e As EventArgs)
    Dim con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
    Dim cmd As SqlCommand = Nothing

    For i As Integer = 0 To GridAddSCode.Rows.Count - 1
        Dim txtCustomerId As TextBox = TryCast(GridAddSCode.Rows(i).FindControl("txtCustomerId"), TextBox)
        Dim txtCountry As TextBox = TryCast(GridAddSCode.Rows(i).FindControl("txtCountry"), TextBox)
        cmd = New SqlCommand("INSERT INTO CustomerTestDemo(Customerid, Country) VALUES(@Customerid, @Country)", con)
        cmd.Parameters.AddWithValue("@CustomerId", txtCustomerId.Text.Trim())
        cmd.Parameters.AddWithValue("@Country", txtCountry.Text.Trim())
        con.Open()
        cmd.ExecuteNonQuery()
        con.Close()
    Next

    cmd = New SqlCommand("SELECT CustomerId, Country FROM CustomerTestDemo", con)
    Dim da As SqlDataAdapter = New SqlDataAdapter(cmd)
    Dim dt As DataTable = New DataTable()
    da.Fill(dt)
    GridView1.DataSource = dt
    GridView1.DataBind()
End Sub

Screenshot