從PDOStatement對象

Question

獲取PDO

考慮以下幾點：

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

是否有可能從$PDOStatement實例得到$PDO實例？

Answer 1

目前，這是不可能的。儘管PDOStatement對象的每個實例存儲用於創建它（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; 

...它不是通過公共方法暴露。

---

這可能是值得一記，反過來pdo_dbh_t實例可以（至少看起來如此）引用存儲到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;