How to bind ComboBox in C# Windows Application

 Follows Following Steps to Binding ComboBox in C# :

1.Define namespace for sqlconnection 
<using System.Data.SqlClient;>
2.define Object for Binding Source 
<private Binding Source bindingSource1 = new BindingSource();>
3.Define Adapter Object for Adopt data from Database
 < private SqlDataAdapter dataAdapter = new SqlDataAdapter();>
4.Define Connection String for Connection in forms
 < String connectionString = "Data Source=.\\sqlexpress;Initial Catalog=schoolDB;Integrated Security=True"; >
5.Then Adapter Call and pass command and connection that two argument pass 
<dataAdapter = new SqlDataAdapter(selectCommand, connectionString);>
6.Then Sql commandbuilder call for execuate command in the database
 <  SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);>
7.Then DataTable Call for Store the Value in table 
< DataTable table = new DataTable();>
8.Then this data to localize in local System or Space
< table.Locale = System.Globalization.CultureInfo.InvariantCulture;>
9.Then This Table Data fill by adapter
<dataAdapter.Fill(table);>
10.Then Set BindSource to Table
<bindingSource1.DataSource = table;>
11.Then Set ComboBox DisplayMember and ValueMember Property
<ComboBox1.DisplayMember = "School_name";
                ComboBox1.ValueMember = "id";>
12 Then This code to call specific event use function and set DataSource pass a argument.
< this.Load += new System.EventHandler(button1_Click);

               ComboBox1.DataSource = bindingSource1; 

 GetData("select School_name,id from School_info where id=13");

>
Thus You Successfully Bind the combo Box to Data Base

Example Source code

---

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace ComboBox
{
    public partial class buttionEvent : Form
    {
        private BindingSource bindingSource1 = new BindingSource();
        private SqlDataAdapter dataAdapter = new SqlDataAdapter();

        private void GetData(string selectCommand)
        {
            try
            {

                String connectionString = "Data Source=.\\sqlexpress;Initial Catalog=schoolDB;Integrated Security=True";

                dataAdapter = new SqlDataAdapter(selectCommand, connectionString);


                SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);


                DataTable table = new DataTable();

                table.Locale = System.Globalization.CultureInfo.InvariantCulture;

                dataAdapter.Fill(table);

                bindingSource1.DataSource = table;
                ComboBox1.DisplayMember = "School_name";
                ComboBox1.ValueMember = "id";


            }
            catch (SqlException)
            {
                MessageBox.Show("To run this example, replace the value of the " +
                    "connectionString variable with a connection string that is " +
                    "valid for your system.");
            }
        }
        public buttionEvent()
        {
            InitializeComponent();
        
          
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Load += new System.EventHandler(button1_Click);

            this.Text = "DataGridView databinding and updating demo";
            ComboBox1.DataSource = bindingSource1;
            ComboBox1.Visible = true;



            GetData("select School_name,id from School_info where id=13");
        }
    }
}