Show total markers for a specific map

WP Google Maps

add_shortcode( 'wpgmza_total_markers', 'wpgmza_total_marker_count' );

function wpgmza_total_marker_count( $atts ){

    $atts = shortcode_atts( array(
        'id' => 1,
    ), $atts, 'wpgmza_total_markers' );

    $map_id = intval( $atts['id'] );

    global $wpdb;
    
    $table_name = $wpdb->prefix.'wpgmza';

    $sql = "SELECT count(*) as total_markers FROM `$table_name` WHERE `map_id` = '$map_id'";

    $total_count = $wpdb->get_row( $sql );

    if( $total_count ){
        return $total_count->total_markers;
    } else {
        return 0;
    }

}