问题描述
我有一个旧的 PHP/MySQL 应用程序，它调用 mysql_connect().大量现有的下游代码使用此连接直接或通过包装器进行 mysql_query() 调用.
I have a legacy PHP/MySQL app that calls mysql_connect(). Tons of existing downstream code makes mysql_query() calls, either directly or through wrappers, using this connection.
对于我在应用程序上开发的新代码，我想开始使用 PDO.
For new code that I develop on the app, I would like to start using PDO.
如果我使用相同的主机/用户/密码/dbname 凭据建立 PDO 连接，我是否很幸运，在幕后，PHP 将重新使用原始连接?或者 PHP 是否会创建到服务器的两个不同的连接(不合需要，尽管完全可以理解)?
If I make a PDO connection using the same host/user/pass/dbname credentials, might I be so lucky that under the hood, PHP will re-use the original connection? Or will PHP create two distinct connections to the server (undesirable, albeit totally understandable)?
谢谢！
推荐答案
如果您使用两个不同的 API(即 mysql_* 和 PDO)，PHP 将生成两个不同的连接.
If you are using two different APIs (i.e. mysql_* and PDO), PHP will generate two different connections.
并且，作为证明"，请考虑这部分代码:
And, as a "proof", consider this portion of code :
$db = mysql_connect('localhost', 'USER', 'PASSWORD');
$pdo = new PDO('mysql://@localhost/astralblog', 'USER', 'PASSWORD');
sleep(5);
运行这将在 MySQL 服务器上产生两个不同的连接——它将休眠 5 秒:
Running this will cause two distinct connections, on the MySQL server -- which will sleep for 5 seconds :
mysql> show processlist;
+----+------------+-----------------+------------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------------+-----------------+------------+---------+------+-------+------------------+
| 41 | astralblog | localhost:46551 | astralblog | Sleep | 188 | | NULL |
| 42 | astralblog | localhost:46552 | astralblog | Sleep | 188 | | NULL |
| 43 | astralblog | localhost | astralblog | Query | 0 | NULL | show processlist |
| 64 | astralblog | localhost | NULL | Sleep | 4 | | NULL |
| 65 | astralblog | localhost | NULL | Sleep | 4 | | NULL |
+----+------------+-----------------+------------+---------+------+-------+------------------+
5 rows in set (0,00 sec)
(有问题的连接是最后两个，在我启动PHP脚本时出现，5秒后消失)
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