VB.Net - How can I check if a primary key exists in an Access DB

I want to check in an Access Database if a primary key exists using VB.Net & OleDb:

• By primary key name

• 开发者_如何学CBy number of fields as primary keys

From here:

Public Shared Function getKeyNames(tableName As [String], conn As DbConnection) As List(Of String)
    Dim returnList = New List(Of String)()


    Dim mySchema As DataTable = TryCast(conn, OleDbConnection).GetOleDbSchemaTable(OleDbSchemaGuid.Primary_Keys, New [Object]() {Nothing, Nothing, tableName})


    ' following is a lengthy form of the number '3' :-)
    Dim columnOrdinalForName As Integer = mySchema.Columns("COLUMN_NAME").Ordinal

    For Each r As DataRow In mySchema.Rows
        returnList.Add(r.ItemArray(columnOrdinalForName).ToString())
    Next

    Return returnList
End Function