In this article I will explain you how to populate the data in combobox on the selection of another combobox.
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 ComboboxSelection
{
public partial class Form1 : Form
{
//Connection String
string con = “Data Source=(local);Initial Catalog=Northwind;Integrated Security=True”;
public Form1()
{
InitializeComponent();
}
private voidForm1_Load(object sender, EventArgs e)
{
//populate data from database
string sql = “SELECT * From BikeType order by idx”;
SqlConnection cnn = new SqlConnection(con);
SqlDataReader rd;
cnn.Open();
SqlCommand cmd = new SqlCommand(sql, cnn);
rd = cmd.ExecuteReader();
comboBox1.Items.Clear();
while (rd.Read())
{
comboBox1.Items.Add(new ItemData(Convert.ToInt32(rd[“idx”]),
rd[“BikeType”].ToString()));
}
cnn.Close();
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgse)
{
//populate the data from database on the selection of another combobox
int Bk=((ItemData)comboBox1.SelectedItem).ID;
string sql = “SELECT * From BikeName where BikeT=” + Bk + ” “;
SqlConnection cnn = new SqlConnection(con);
SqlDataReader rd;
cnn.Open();
SqlCommand cmd = new SqlCommand(sql, cnn);
rd = cmd.ExecuteReader();
comboBox2.Items.Clear();
while (rd.Read())
{
comboBox2.Items.Add(new ItemData(Convert.ToInt32(rd[“idx”]), rd[“BikeName”].ToString()));
}
cnn.Close();
}
public structItemData
{
public intID;
public stringEmpName;
public ItemData(int_ID, string _EMName)
{
ID = _ID;
EmpName = _EMName;
}
public overridestring ToString()
{
returnthis.EmpName;
}
}
}
}
}
