dropdownlist selected value from database values

Question

if (connection.State == ConnectionState.Closed)

connection.Open();

command = new SqlCommand();

command.CommandText = "sp_Get_ControlValues";

command.CommandType = CommandType.StoredProcedure;

command.Connection = connection;

command.Parameters.AddWithValue("@uid", uid);

SqlDataAdapter daPack = new SqlDataAdapter(command);

DataSet dsPack = new DataSet();

daPack.Fill(dsPack);

//ddlPackPeriod.DataSource = dsPack;

//ddlPackName.DataSource = dsPack;

//ddlPackPeriod.DataTextField = "PackagePeriod";

//ddlPackName.DataTextField = "PackageName";

txtOldExpDate.Text = dsPack.Tables[0].Rows[0]["OldExpiryDate"].ToString();

txtNoOfExtConn.Text = dsPack.Tables[0].Rows[0]["NoOfExtraConn"].ToString();

txtAmntToPay.Text = dsPack.Tables[0].Rows[0]["Balance"].ToString();

ddlPackPeriod.DataBind();

ddlPackName.DataBind();

 

In 'pageload'  iam alredy binded those two dropdowns and those dropdowns are cascading

 

so when I click on 'Suearch' button I just want to show as selected  of  'UserId' col values

so How?