从PDOStatement对象

Question

获取PDO

考虑以下几点：

$PDOStatement = $PDO->prepare($query); 

是否有可能从$PDOStatement实例得到$PDO实例？

Answer 1

目前，这是不可能的。尽管PDOStatement对象的每个实例存储用于创建它（quoting lxr for PHP 5.6）一DB手柄：

/* represents a prepared statement */ 
543 struct _pdo_stmt_t { 
544 /* these items must appear in this order at the beginning of the 
545  struct so that this can be cast as a zend_object. we need this 
546  to allow the extending class to escape all the custom handlers 
547  that PDO declares. 
548 */ 
549 zend_object std; 
550 
... 
572 /* we want to keep the dbh alive while we live, so we own a reference */ 
573 zval database_object_handle; 
574 pdo_dbh_t *dbh; 

...它不是通过公共方法暴露。

---

这可能是值得一记，反过来pdo_dbh_t实例可以（至少看起来如此）引用存储到pdo_stmt_t（link）的：

427 /* represents a connection to a database */ 
428 struct _pdo_dbh_t { 
... 
501 /* when calling PDO::query(), we need to keep the error 
502  * context from the statement around until we next clear it. 
503  * This will allow us to report the correct error message 
504  * when PDO::query() fails */ 
505 pdo_stmt_t *query_stmt;