Fetch Values from Sql

try this it will work

on ComboBox selected index changed event write this code

SqlConnection con = new SqlConnection("Data Source=C3;Initial Catalog=Books;Persist Security Info=True;User ID=sa;Password=p@ssw0rd");
        SqlCommand cmd = new SqlCommand("select EmpName from EmpInfo where EmpId='"+ComboBox1.SelectedItem+"'",con);
        con.Open();
        string str = Convert.ToString(cmd.ExecuteScalar());
        con.Close();

        Label1.Text = str;//Here In Label u will get Employee Name

Note:use Namespace using System.Data.SqlClient;

Hi Sudhir,
  Generate SelectedValueChanged event for comboBox and then implement below code in this event,
 Try this :
  private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
  {
  SqlDataReader dr;
  SqlCommand cmd;
  //replace your connection
  SqlConnection con = new SqlConnection("Data Source=.//SQLEXPRESS;Initial Catalog=DBName;User ID=Admin;Password=Admin");
  try
  {
  con.Open();
  string qry = "Select EmpName from table where EmpCode =" + comboBox1.SelectedItem;
  cmd = new SqlCommand(qry, con);
  dr = cmd.ExecuteReader();
  while (dr.Read())
  {
  MessageBox.Show(dr.GetString(0)); //here u will get the employee name
  }
  dr.Close();
 
  }
  catch (Exception ex)
  {
  MessageBox.Show(ex.Message);
  }
  finally
  {
  con.Close();
  }
  }

Write select query like
Select EmployeeName From Table Where EmpolyeeCode=Combobox1.SelectedValue;