Parameterized Or Array With This SQL?

I have two CheckBoxList controls. One CheckBoxList is a group of area codes as they apply to our customers, and the second CheckBoxList is a group of categories of those customers. The code below works fine with either CheckBoxList as a standalone (this code applies to the Area Codes selection), but what I need is the VB code to combine the choices a user makes in both CheckBoxLists. Is this where parameterized SQL comes into play? Or can I/should I use an array statement to combine both CheckBoxList choices? Sometimes a user will select nothing in one CBL and a few choices in the other, or vice versa, or a handful of choices in both CBLs, so that they might want only customers in, say two area codes and then only the selected categories of those area codes.  Need help on this one, thanks...

Protected Sub btn_CustomerSearchCombine_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_CustomerSearchCombine.Click
        Dim ACSelections As Boolean = False
        Dim ACItem As ListItem
        For Each ACItem In cbl_CustomerSearchAREA.Items
            If ACItem.Selected Then
                ACSelections = True
            End If
        Next

        If ACSelections = True Then
            Dim ACSqlString As String
            ACSqlString = "SELECT Customers.CustomerID, Customers.CustomerName, Customers.CategoryID, Customers.EstHours, Customers.Locality, Categories.Category FROM Customers INNER JOIN Categories ON Customers.CategoryID = Categories.CategoryID WHERE "

            For Each ACItem In cbl_CustomerSearchAREA.Items
                If ACItem.Selected Then
                    ACSqlString &= "Customers.AreaCodeID = '" & ACItem.Value & "' OR "
                End If
            Next

            ACSqlString = Left(ACSqlString, Len(ACSqlString) - 4)
            ACSqlString &= "ORDER By Customers.CustomerName"
            sql_CustomerSearchGrid.SelectCommand = ACSqlString
        End If
End Sub