How to bind dropdownlist with the tables

First you need to understand the flow of DropDownList[^]. It contains two important properties:
1. DataValueField
2. DataTextField

For the DataValueField and DataTextField properties, if you only set value to one of them, the other property is also set to the same value. If you only specify DropDownList1.DataTextField = "CategoryName", both the display text and value of each DropDownList item are set to Name. If you only specify DropDownList1. DataValueField = "CategoryID", both the display text and value of each DropDownList item are set to ID.
See this:

<asp:dropdownlist id="DropDownList1" runat="server" xmlns:asp="#unknown">
</asp:dropdownlist>

protected void Page_Load(object sender, EventArgs e)
{
    using (SqlConnection conn = new SqlConnection(@"Data Source=.;Initial Catalog=testing;Integrated Security=True;"))
    {
        SqlCommand cmd = new SqlCommand("select CategoryID,CategoryName from Categories",conn);

        DataTable dt = new DataTable();

        SqlDataAdapter sda = new SqlDataAdapter(cmd);
        sda.Fill(dt);
        DropDownList1.DataSource = dt;
        DropDownList1.DataTextField = "CategoryName";
        DropDownList1.DataValueField = "CategoryID";
        DropDownList1.DataBind();
    }
}

--Amit

You can use following method for all of your tables:(If you want data of all five tables in one drop down)
1. Add all your tables to your DataSet.
2. use following code:

foreach(Table yourTable in DataSet.Tables)
{
    foreach(DataRow row in yourTable.Rows)
    {
          ListItem item = new ListItem();
          item.Text=row["your column"].ToString();
          item.Value=row["your column"].ToString();
          yourDropDownList.Items.Add(item);
    }
}

If you want different tables in different DropDownList then use Solution 2 mentioned above.