In this article I will explain with an example, how to populate DropDownList with selected value in EditItemTemplate of GridView in ASP.Net using C# and VB.Net.
 
 

Database

I have made use of the following table Customers with the schema as follows.
Populate DropDownList with Selected Value in EditItemTemplate of GridView in ASP.Net
 
I have already inserted few records in the table.
Populate DropDownList with Selected Value in EditItemTemplate of GridView in ASP.Net
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

HTML Markup

The HTML Markup consists of following controls:
GridView – For displaying data.

Columns

The GridView consists of one BoundField column, one TemplateField column and one CommandField column.
TemplateField – The TemplateField column consists of ItemTemplate and EditItemTemplate.
ItemTemplate – The ItemTemplate consists of a Label.
EditItemTemplate – The EditItemTemplate consists of a DropDownList.
 
The GridView has been assigned with the following property:
DataKeyNames – For permitting to set the names of the Column Fields, that we want to use in code but do not want to display it. Example Primary Keys, ID fields, etc.
Note: For more details on how to use DataKeyNames, please refer my article DataKeyNames in GridView example in ASP.Net in GridView example in ASP.Net.
 
The GridView has been assigned with the following event handlers i.e. OnRowEditing, OnRowDataBound, OnRowUpdating and OnRowCancelingEdit.
 
The CommandField column has been assigned with the following property:
ShowEditButton – For displaying Edit LinkButton.
<asp:GridView ID="gvCustomers" DataKeyNames="CustomerId" runat="server" AutoGenerateColumns="false"
    OnRowEditing="OnRowEditing" OnRowDataBound="OnRowDataBound" OnRowUpdating="OnRowUpdating"
    OnRowCancelingEdit="OnRowCancelingEdit">
    <Columns>
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:TemplateField HeaderText="Country">
            <ItemTemplate>
                <asp:Label ID="lblCountry" runat="server" Text='<%# Eval("Country")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:DropDownList ID="ddlCountry" runat="server"></asp:DropDownList>
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:CommandField ShowEditButton="True" />
    </Columns>
</asp:GridView>
 
 

Namespaces

You will need to import the following namespaces.
C#
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
 
VB.Net
Imports System.Data
Imports System.Configuration
Imports System.Data.SqlClient
 
 

Populating the GridView

Inside the Page_Load event handler, the BindGrid method is called where the records are fetched from the Customers Table of the SQL Server database and the GridView is populated.
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}
 
private void BindGrid()
{
    string sql = "SELECT CustomerId, Name, Country FROM Customers";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter(sql, con))
        {
            using (DataTable dt = new DataTable())
            {
                sda.Fill(dt);
                gvCustomers.DataSource = dt;
                gvCustomers.DataBind();
            }
        }
    }
}
 
VB.Net
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Me.BindGrid()
    End If
End Sub
 
Private Sub BindGrid()
    Dim sql As String = "SELECT CustomerId, Name, Country FROM Customers"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using sda As SqlDataAdapter = New SqlDataAdapter(sql, con)
            Using dt As DataTable = New DataTable()
                sda.Fill(dt)
                gvCustomers.DataSource = dt
                gvCustomers.DataBind()
            End Using
        End Using
    End Using
End Sub
 
 

Binding the DropDownList in GridView using C# and VB.Net

Inside the OnRowDataBound event handler, a check is performed whether the selected row is DataRow and it is in edit mode.
Then, the DropDownList control is referenced and it is populated using DISTINCT values of Country from the Customers Table.
The Text and Value properties are set and country is selected using Eval method of DataBinder class.
Finally, the selected Country is set in the DropDownList control and made selected.
C#
protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow && gvCustomers.EditIndex == e.Row.RowIndex)
    {
        DropDownList ddlCountry = (DropDownList)e.Row.FindControl("ddlCountry");
        string sql = "SELECT DISTINCT Country FROM Customers";
        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter(sql, con))
            {
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    ddlCountry.DataSource = dt;
                    ddlCountry.DataTextField = "Country";
                    ddlCountry.DataValueField = "Country";
                    ddlCountry.DataBind();
                    string selectedCountry = DataBinder.Eval(e.Row.DataItem, "Country").ToString();
                    ddlCountry.Items.FindByValue(selectedCountry).Selected = true;
                }
            }
        }
    }
}
 
VB.Net
Protected Sub OnRowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If e.Row.RowType = DataControlRowType.DataRow AndAlso gvCustomers.EditIndex = e.Row.RowIndex Then
        Dim ddlCountry As DropDownList = CType(e.Row.FindControl("ddlCountry"), DropDownList)
        Dim sql As String = "SELECT DISTINCT Country FROM Customers"
        Dim  constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using con As SqlConnection = New SqlConnection(constr)
            Using sda As SqlDataAdapter = New SqlDataAdapter(sql, con)
                Using dt As DataTable = New DataTable()
                    sda.Fill(dt)
                    ddlCountry.DataSource = dt
                    ddlCountry.DataTextField = "Country"
                    ddlCountry.DataValueField = "Country"
                    ddlCountry.DataBind()
                    Dim selectedCountry As String = DataBinder.Eval(e.Row.DataItem, "Country").ToString()
                    ddlCountry.Items.FindByValue(selectedCountry).Selected = True
                End Using
            End Using
        End Using
    End If
End Sub
 
 

Editing in GridView

When the Edit Button is clicked, the EditIndex of the GridView is updated with the RowIndex of the GridViewRow being edited and the GridView is again populated with data.
C#
protected void OnRowEditing(object sender, GridViewEditEventArgs e)
{
    gvCustomers.EditIndex = e.NewEditIndex;
    this.BindGrid();
}
 
VB.Net
Protected Sub OnRowEditing(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
    gvCustomers.EditIndex = e.NewEditIndex
    Me.BindGrid()
End Sub
 
 

Canceling the Edit in GridView

When the Cancel Button is clicked, the EditIndex is set to -1 and the GridView is again populated with data.
C#
protected void OnRowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
    gvCustomers.EditIndex = -1;
    this.BindGrid();
}
 
VB.Net
Protected Sub OnRowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
    gvCustomers.EditIndex = -1
    Me.BindGrid()
End Sub
 
 

Updating the GridView

When the Update Button is clicked, the CustomerId (primary key) is fetched from the DataKeys property of GridView and Country is fetched from the DropDownList Control.
Finally, these values are updated in the SQL Server database using ExecuteNonQuery method.
Note: For more details on how to use ExecuteNonQuery method, please refer my article Understanding SqlCommand ExecuteNonQuery in C# and VB.Net.
 
C#
protected void OnRowUpdating(object sender, GridViewUpdateEventArgs e)
{
    string country = (gvCustomers.Rows[e.RowIndex].FindControl("ddlCountry") as DropDownList).SelectedItem.Value;
    string customerId = gvCustomers.DataKeys[e.RowIndex].Value.ToString();
    string sql = "UPDATE Customers SET Country = @Country WHERE CustomerId = @CustomerId";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(sql, con))
        {
            cmd.Parameters.AddWithValue("@CustomerId", customerId);
            cmd.Parameters.AddWithValue("@Country", country);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
            Response.Redirect(Request.Url.AbsoluteUri);
        }
    }
}
 
VB.Net
Protected Sub OnRowUpdating(ByVal sender As Object, ByVal e As GridViewUpdateEventArgs)
    Dim country As String = (TryCast(gvCustomers.Rows(e.RowIndex).FindControl("ddlCountry"), DropDownList)).SelectedItem.Value
    Dim customerId As String = gvCustomers.DataKeys(e.RowIndex).Value.ToString()
    Dim sql As String = "UPDATE Customers SET Country = @Country WHERE CustomerId = @CustomerId"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(sql, con)
            cmd.Parameters.AddWithValue("@CustomerId", customerId)
            cmd.Parameters.AddWithValue("@Country", country)
            con.Open()
            cmd.ExecuteNonQuery()
            con.Close()
            Response.Redirect(Request.Url.AbsoluteUri)
        End Using
    End Using
End Sub
 
 

Screenshot

Populate DropDownList with Selected Value in EditItemTemplate of GridView in ASP.Net
 
 

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