How to Retrieve data from database to fill Textboxes when selected index is changed in Dropdownlist using Windows Form C#.Net.

To implement this concept you need to follow the below steps :

Step1 :

First you need to design a table in Ms Access 2007 to retrieve the data from database.

Step2:

On the File menu, click New Project. Select Windows Forms Application as your project type.

Design the Form using controls from Toolbox.

Step3:

Now open the Form.cs page and write the following source code.

 Form.cs 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.OleDb;

namespace Sample

{

    public partial class Sample_Example : Form

    {

        OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\App_Data\SampleDB.accdb; Jet OLEDB:Database Password=1234;Persist Security Info=False");

        public Sample_Example()

        {

            InitializeComponent();

            ClientBind();

        }

        private void DropdownlistBind()

        {

            con.Open();

            OleDbDataAdapter da = new OleDbDataAdapter("Select ID, Client_Name from SampleDB_CreateClient", con);

            DataTable dt = new DataTable();

            da.Fill(dt);

            DataRow dr;

            dr = dt.NewRow();

            dr.ItemArray = new object[] { 0, "---Select Client Name---" };

            dt.Rows.InsertAt(dr, 0);

            cmbClientName.DisplayMember = "Client_Name";

            cmbClientName.ValueMember = "ID";

            cmbClientName.DataSource = dt;

            con.Close();

        }

  

        private void Clear()

        {

            cmbClientName.SelectedValue = 0;

            txtClientName.Text = string.Empty;

            txtContactPerson.Text = string.Empty;

            txtAdress.Text = string.Empty;

            txtContactNo.Text = string.Empty;

            txtEmailId.Text = string.Empty;

        }

        private void cmbClientName_SelectedIndexChanged(object sender, EventArgs e)

        {

            if (cmbClientName.SelectedIndex > 0)

            {

                con.Open();

                int id = Convert.ToInt32(cmbClientName.SelectedValue);

                OleDbCommand cmd = new OleDbCommand("select * from SampleDB_CreateClient where ID = " + id, con);

                cmd.CommandType = CommandType.Text;

                OleDbDataAdapter da = new OleDbDataAdapter(cmd);

                DataTable dt = new DataTable();

                da.Fill(dt);

                txtClientName.Text = dt.Rows[0].ItemArray[1].ToString();

                txtContactPerson.Text = dt.Rows[0].ItemArray[2].ToString();

                txtAdress.Text = dt.Rows[0].ItemArray[3].ToString();

                txtContactNo.Text = dt.Rows[0].ItemArray[4].ToString();

                txtEmailId.Text = dt.Rows[0].ItemArray[5].ToString();

                con.Close();

            }

            else

            {

                Clear();

            }

        }

     }
  }

Step4:
Now build the Solution and Debug it for the output.