在WooCommerce中显示基于自定义表的自定义字段值

function create_custom_table() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'custom_table';

    $charset_collate = $wpdb->get_charset_collate();

    $sql = "CREATE TABLE $table_name (
        id mediumint(9) NOT NULL AUTO_INCREMENT,
        product_id mediumint(9) NOT NULL,
        custom_field_value text NOT NULL,
        PRIMARY KEY  (id)
    ) $charset_collate;";

    require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
    dbDelta( $sql );
}
register_activation_hook( __FILE__, 'create_custom_table' );

function add_custom_field_value( $product_id ) {
    global $wpdb;
    $table_name = $wpdb->prefix . 'custom_table';

    $custom_field_value = 'Some custom value'; // 这里可以是动态获取的值

    $wpdb->insert(
        $table_name,
        array(
            'product_id' => $product_id,
            'custom_field_value' => $custom_field_value,
        )
    );
}
add_action( 'woocommerce_new_product', 'add_custom_field_value' );
add_action( 'woocommerce_update_product', 'add_custom_field_value', 10, 2 );

function display_custom_field_value() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'custom_table';
    $product_id = get_the_ID();

    $custom_field_value = $wpdb->get_var( $wpdb->prepare(
        "SELECT custom_field_value FROM $table_name WHERE product_id = %d",
        $product_id
    ) );

    if ( $custom_field_value ) {
        echo '<p>Custom Field Value: ' . esc_html( $custom_field => Value ) . '</p>';
    }
}
add_action( 'woocommerce_single_product_summary', 'display_custom_field_value', 25 );