可以使用以下查询：

global $wpdb;
$min_price = 3800; // Set the minimum price filter value
$max_price = null; // Set the maximum price filter value (null if empty)
$query = $wpdb->prepare("
    SELECT p.post_id, p.meta_value AS min_price, q.meta_value AS max_price
    FROM {$wpdb->prefix}postmeta AS p
    JOIN {$wpdb->prefix}postmeta AS q ON p.post_id = q.post_id
    WHERE p.meta_key = 'min_price'
        AND q.meta_key = 'max_price'
        AND (
            (%d IS NULL OR p.meta_value <= %d)
            AND (%d IS NULL OR q.meta_value >= %d)
        )
", $min_price, $min_price, $max_price, $max_price);

$results = $wpdb->get_results($query);

if ($results) {
    foreach ($results as $result) {
        $post_id = $result->post_id;
        $min_price = $result->min_price;
        $max_price = $result->max_price;

        // Process the retrieved product data as needed
        // ...
    }
} else {
    echo 'No products found.';
}

SELECT p.*
FROM wp_posts p
JOIN wp_postmeta pm_min ON p.ID = pm_min.post_id AND pm_min.meta_key = 'min_price'
JOIN wp_postmeta pm_max ON p.ID = pm_max.post_id AND pm_max.meta_key = 'max_price'
WHERE pm_min.meta_value <= 4500
  AND pm_max.meta_value >= 6000
  AND p.post_type = 'product'
  AND p.post_status = 'publish';