Connecting to Multiple Databases and Performing Cross‑Database Queries in ThinkPHP

This article explains how to connect to multiple databases in ThinkPHP and perform cross‑database queries.

Method 1: Call Db::connect() with either a DSN string or a configuration array. Example:

Db::connect('mysql://root:[email protected]:3306/thinkphp#utf8');

Db::connect([
  'type'     => 'mysql',
  'hostname' => '127.0.0.1',
  'database' => 'thinkphp',
  'username' => 'root',
  'password' => '',
  'hostport' => '',
  'charset'  => 'utf8',
  'prefix'   => 'think_'
]);

For detailed usage, refer to the ThinkPHP5 manual.

Method 2: Add multiple database configurations in the application config file, e.g., 'database1' => [...] and 'database2' => [...]. Connect by name with Db::connect('database1') and then use the returned instance for queries:

$db = Db::connect('database1');
$db->name('table')->select();

Cross‑database query – Method 1: Use Db::query() with fully qualified table names ( database.table) in raw SQL, for example:

select * from database1.table1 as t1 inner join database2.table2 as t2 where t1.id = t2.id;

Cross‑database query – Method 2: Query one database, iterate over the result set, and for each row query the second database, then combine the data as needed.

For more information, see the ThinkPHP5 complete development manual at https://www.kancloud.cn/manual/thinkphp5/118059 .