How to call serial one by one when enter text box

Thanks for replying soon.Actually my database fields are Hh,Slno,Name,Sex. In data nature look as below :
        Hh          Slno        Name        Sex
S0010001         01               A        Male
S0010001         02               B        female
S0010001         03               C        Male

So, When I will put Hh then Slno 01 will be the show automatically into txtSlNo.Text box. After that Hh will disbale and slno 02 will be appear if I press enter after that serial 03 like that. Other variable will show automatically.

Hey Prasanta,

It's really difficult to understand your problem but I am making a guess that you want to bind a DropDown List to your Database, in this dropdown "household ID" will be shown and as you select any of the ID than related  data will be shown in the other Textboxes. If this is the problem then you can use this code:

SqlConnection x;
    SqlCommand y;
    SqlDataReader z;

    SqlDataAdapter y1;
    DataTable dt;
    protected void Page_Load(object sender, EventArgs e)
    {
        x = new SqlConnection(@"data source=AGILE-A4D936161\SQLEXPRESS;integrated security=sspi;initial catalog=master");
        x.Open();
        if (!Page.IsPostBack)
        {
            y1 = new SqlDataAdapter("select empno from emp", x);
            dt = new DataTable();
            y1.Fill(dt);
            DropDownList1.DataSource = dt;
            DropDownList1.DataTextField = "empno";
            DropDownList1.DataBind();
        }
        x.Close(); 
    }
    
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        x.Open();
        y = new SqlCommand("select * from emp where empno=" + DropDownList1.SelectedItem.Text, x);
        z = y.ExecuteReader();
        while (z.Read())
        {
            TextBox2.Text = z[1].ToString();
            TextBox3.Text = z[2].ToString();  
        }
        x.Close(); 
    }