Populate (Bind) ComboBox in DataGridView in Windows Forms (WinForms) Application using C# and VB.Net

Hi Prasunjeet,

I have created a sample that full fill your requirement.

Namespace

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

 Code

private void Form1_Load_1(object sender, EventArgs e)
{
    string countryQuery = "SELECT CountryID,CountryName FROM Country";
    this.cbCountry.DisplayMember = "CountryName";
    this.cbCountry.ValueMember = "CountryID";
    this.cbCountry.DataSource = this.PopulateComboBox(countryQuery);
    string stateQuery = "SELECT StateId,StateName FROM States";
    this.cbState.DisplayMember = "StateName";
    this.cbState.ValueMember = "StateId";
    this.cbState.DataSource = this.PopulateComboBox(stateQuery);
}

private DataTable PopulateComboBox(string sqlQuery)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(sqlQuery, conn))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                DataTable dt = new DataTable();
                da.Fill(dt);
                return dt;
            }
        }
    }
}

Screenshot

Hope this will help you.