VB.net SQL Find first and last text items in a column

Hi

I use the following VB.net code to find the maximum value in numeric and date columns
How do I find the maximum or minimum of an text column where for instance "Albert" would
be the minimum and "Zach" would be the maximum

 Function oMaximum_in_Column(ByVal oTableName As String, ByVal oColumnName As String) As String
        Try

            Dim oSQL As String

            oSQL = "Select Max([" & oColumnName & "]) As MyMax From [" & oTableName & "]"

            Dim cn As New SqlConnection(Globals.ThisAddIn.oRIGHT.lblConnectionString.Text)
            Dim cmd As New SqlCommand(oSQL, cn)
            cmd.CommandTimeout = My.Settings.Timeout
            cn.Open()

            oMaximum_in_Column = cmd.ExecuteScalar.ToString

        Catch ex As Exception
            oMaximum_in_Column = "N/A"
        End Try
    End Function