function seconddb() {
    global $seconddb;
    $seconddb = new wpdb('username','password','database name','localhost');
}
add_action('init','seconddb');
// add the shortcode [pontoon-table], tell WP which function to call
add_shortcode( 'pontoon-table', 'pontoon_table_shortcode' );

// add the shortcode [pontoon-table], tell WP which function to call
add_shortcode( 'pontoon-table', 'pontoon_table_shortcode' );

// this function generates the shortcode output
function pontoon_table_shortcode( $args ) {

    global $seconddb;
    // Shortcodes RETURN content, so store in a variable to return
    $content = '<table>';
    $content .= '</tr><th>Week Beginning</th><th>Data Type</th><th>Monday</th><th>Tuesday</th><th>Wednesday</th><th>Thursday</th><th>Friday</th><th>Saturday</th><th>Sunday</th><th>Weekly Total</th><th>Previous Week Totals</th></tr>';
    $results = $seconddb->get_results( ' SELECT * FROM seconddb_PontoonBoats_LineOne_2Log' );
    foreach ( $results AS $row ) {
        $content .= '<tr>';
        // Modify these to match the database structure
        $content .= '<td>' . $row->{'Week Beginning'} . '</td>';
        $content .= '<td>' . $row->{'Data Type'} . '</td>';
        $content .= '<td>' . $row->Monday . '</td>';
        $content .= '<td>' . $row->Tuesday . '</td>';
        $content .= '<td>' . $row->Wednesday . '</td>';
        $content .= '<td>' . $row->Thursday . '</td>';
        $content .= '<td>' . $row->Friday . '</td>';
        $content .= '<td>' . $row->Saturday . '</td>';
        $content .= '<td>' . $row->Sunday . '</td>';
        $content .= '<td>' . $row->{'Weekly Total'} . '</td>';
        $content .= '<td>' . $row->{'Previous Week Totals'} . '</td>';
        $content .= '</tr>';
    }
    $content .= '</table>';

    // return the table
    return $content;
}