如何使用 PDO 跨两个数据库运行带有连接的查询 [英] How to run a query with a join accross two databases with PDO

问题描述

我有两个 PDO 对象代表两个数据库，pdo1 和 pdo2，声明如下:

I've got two PDO objects representing two databaes, pdo1 and pdo2, declared as per the following:

try {
    $pdo1 = new PDO('mysql:host=localhost;dbname=database1', 'user', 'password');
    $pdo1->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo1->exec('SET NAMES "utf8"');
}

^ 我对 $pdo2 也做了同样的事情，它是第二个数据库.

^ And I've done the same for $pdo2 which is for the second database.

到目前为止，我访问数据库的方式如下:

The way I've been accessing the database so far has been like the following:

try {
     $sql   = 'SELECT * from table1';
     $result = $pdo1->query($sql);  
}

现在我想运行一个查询，其中两个表跨两个数据库连接.如何使用两个 pdo 对象执行此操作?这是我所拥有的，但我坚持如何做我放置星号的 $result 部分:

Now I want to run a query where two tables are joined across two databases. How can I do this with the two pdo objects? Here's what I've got, but I'm stuck on how to do the $result part where I've put asterixis:

try {
     $sql   = 'SELECT database1.table1.name FROM database1.table1 LEFT JOIN database2.table2
               ON database1.table1.userid = database2.table2.userid';
     $result = $pdo***->query($sql);    
     }

以前，它会引用 $pdo1 或 $pdo2，但是如何组合该部分以从组合的 pdo 对象中提取结果?

Previously, it would refer to either $pdo1 or $pdo2, but how do you combine that part to pull the result from combined pdo objects?

推荐答案

使用one连接，然后做一个类似

Use one connection, then do a query like

SELECT ... FROM db1.tbl1 JOIN db2.tbl2 ...

(您将需要访问两个数据库的权限.)

(You will need permissions to access both databases.)

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