我需要连接同一主机中的另一个数据库并返回产品值（Woocomece）。返回值为空

add_shortcode(\'product_project_test\', \'product_project_test\');
function product_project_test() {   
    $mydbTest = new wpdb(\'user\',\'password\',\'dbname\',\'localhost\');

    $result= $mydbTest->get_results("SELECT `meta_value` FROM `wp_postmeta` WHERE \'post_id\' = 5338 AND \'meta_key\' = \'_sale_price\'");
    $price = $result[0];
    $price = number_format($price, 2, \'.\', \',\');

    return \'$ \'.$price;

}

SQL Consult

SELECT `meta_value` FROM `wp_postmeta` WHERE `POST_ID` = 5338 AND `meta_key` = \'_sale_price\'

Update - my Solution works

add_shortcode(\'product_project_test\', \'product_project_test\');
function product_project_test() {   
    $mydbTest = new wpdb($userdb,$mypass,$mydb,\'localhost\');
    $query = "SELECT * FROM wp_postmeta WHERE post_id=608 AND meta_key IN(\'_sale_price\', \'_regular_price\')";

    $results = $mydbTest->get_results($query, ARRAY_A);
        foreach($results as $result){
        if($result[\'meta_key\'] == \'_sale_price\'){
            $price= $result[\'meta_value\'];
            $price= number_format($price, 2, \'.\', \',\');
        } else if($result[\'meta_key\'] == \'_sale_price\'){
            $old_price= $result[\'meta_value\'];
            $old_price= number_format($old_price, 2, \'.\', \',\');
        }
    };

    return \'$ \'.$price;

}