Set Value in TextBox On DropDownList Change depending on SelectedValue

Could you please explain more what numeric value should change and how?

in my dropdownlist the items are manually added as under

DIR, DY DIR, SO,HOD and the same is fed to the field in my database

there is another field named DDPR which is also related to this 

APPT   CODE

DIR      1

dy dir   2

SO        3

HOD      4

THE CODE ONLY IS FED IN THE DDPR  FIELD

i requested u was if i select a appt from my dropdownlist the selected rank should go to the field APPT and at the same time DDPR code as per the appt should be fed to the field DDPR. is it possible

Write a following code in page load event:-

 if (!IsPostBack)         {             SqlConnection cnn = new SqlConnection("Write SQL connection string");             SqlCommand cmd = new SqlCommand("write SQL command ", cnn);             SqlDataAdapter da = new SqlDataAdapter(cmd);             DataSet ds = new DataSet();             da.Fill(ds);             DropDownList1.AppendDataBoundItems = true;             DropDownList1.Items.Add(new ListItem { Text = "---please select--", Value ="0" });             DropDownList1.DataSource = ds;             DropDownList1.DataTextField = "appt database coloum name";             DropDownList1.DataBind();

        }

i tried this code and it works fine

Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
        If DropDownList1.SelectedValue = "Dir" Then
            TextBox1.Text = 1
        End If
        If DropDownList1.SelectedValue = "Dy Dir" Then
            TextBox1.Text = 2
        End If
        If DropDownList1.SelectedValue = "SO" Then
            TextBox1.Text = 3
        End If
        If DropDownList1.SelectedValue = "HOD" Then
            TextBox1.Text = 4
        End If

You can also do with CASE Statement rather use IF ELSE

 Select Case DropDownList1.SelectedValue
            Case "Dir"
                TextBox1.Text = 1
            Case "Dy Dir"
                TextBox1.Text = 2
            Case "SO"
                TextBox1.Text = 3
            Case "HOD"
                TextBox1.Text = 4
        End Select