Getting Dropdownlist selected value in vb.net - sql-server

Question

I am trying to set user account for my system. I have two tables (User and Staff)
And this is the interface for setting up user
the name dropdownlist need to be bound to staff table where I can display a list of staff members. When I insert these data to the user table I need to convert the selected staff name into its ID.
I'm really weak in programming and if possible help me with this.
this is the code I am using
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnUserAdd.Click
If ValidData() Then
Try
cmd.Connection = con
con.Open()
sel_id = Convert.ToString(cmbStaffName.SelectedValue)
cmd.CommandType = System.Data.CommandType.Text
cmd.CommandText = "Insert Into dbo.[User] (User_ID,Employee_ID,User_Name,Password,User_Level) values ('" & txtBoxUserID.Text & "','" & sel_id & "','" & txtBoxUserName.Text & "', '" & txtBoxPassword.Text & "','" & ComboBox1.Text & "')"
cmd.ExecuteNonQuery()
MsgBox("Succesfully Added", MsgBoxStyle.Information, "add")
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
con.Close()
End If
If Not ValidData() Then
Exit Sub
End If
End Sub
Private Sub btnUserUpdate_Click(sender As Object, e As EventArgs) Handles btnUserUpdate.Click
End Sub
Private Sub Setup_User_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'MyHotelManagementSystemDataSet19.Staff' table. You can move, or remove it, as needed.
Me.StaffTableAdapter1.Fill(Me.MyHotelManagementSystemDataSet19.Staff)
'TODO: This line of code loads data into the 'MyHotelManagementSystemDataSet18.Staff' table. You can move, or remove it, as needed.
Me.User_TypeTableAdapter.Fill(Me.MyHotelManagementSystemDataSet17.User_Type)
End Sub
Private Sub cmbStaffName_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbStaffName.SelectedIndexChanged
Try
con.Open()
ds = New DataSet()
cmd = New SqlCommand("select * from Staff", con)
Adapter = New SqlDataAdapter(cmd)
adapter.Fill(ds)
cmbStaffName.DataSource = StaffBindingSource1
cmbStaffName.DisplayMember = "Name"
cmbStaffName.ValueMember = "Employee_ID"
Catch ex As Exception
Finally
con.Close()
End Try
End Sub

Answer 1

Private Sub cmbStaffName_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbStaffName.SelectedIndexChanged
Try
con.Open()
ds = New DataSet()
cmd = New SqlCommand("select * from Staff", con)
Using adapter as New SqlDataAdapter(cmd)
adapter.Fill(ds)
End Using
cmbStaffName.DisplayMember = "Name"
cmbStaffName.ValueMember = "Employee_ID"
cmbStaffName.DataSource = ds
Catch ex As Exception
Finally
con.Close()
End Try
End Sub