How to implement query between two databases in thinkphp

thinkphp is one of the more popular PHP frameworks at present. It can not only quickly build web applications, but also provide convenient functions such as data processing and verification. When we need to connect more than two databases, how to use thinkphp to implement queries between the two databases?

This article will introduce how to link two databases and query them in the thinkphp framework.

1. Configuring the database

In the config folder under the thinkphp framework, find the database.php file, open it and to modify. In this file, we can see the following default database configuration information:

return [
    // 默认数据库配置
    'type'         => 'mysql',
    'hostname'     => '127.0.0.1',
    'database'     => '',
    'username'     => 'root',
    'password'     => '',
    ...

We need to copy it and create a new configuration item for the link to the second database. For example:

return [
    // 默认数据库配置
    'type'         => 'mysql',
    'hostname'     => '127.0.0.1',
    'database'     => '',
    'username'     => 'root',
    'password'     => '',

    // 第二个数据库配置
    'db2' => [
        'type'         => 'mysql',
        'hostname'     => '127.0.0.1',
        'database'     => '',
        'username'     => 'root',
        'password'     => '',
    ],
    ...

In this configuration item, we write the configuration information of the second database in an array named db2, and set the user name, password, host name, etc. information.

2. Connect to the database

Before using the second database, you need to connect it first. We can connect to the database in the initialize() method in the controller.

use think\Db;

class Index
{
    public function initialize()
    {
        Db::connect('db2')->connect();  // 连接第二个数据库
    }

    public function index()
    {
        // 进行查询操作
    }
}

In the above code, the Db::connect() method is used to specify which database to connect to, and "db2" corresponds to the configuration item name added in the previous step. Use the connect() method to connect.

3. Query operation

After connecting, you can use the db() method in the code to specify which database to use for query operations. For example:

use think\Db;

class Index
{
    public function initialize()
    {
        Db::connect('db2')->connect();  // 连接第二个数据库
    }

    public function index()
    {
        $result = Db::name('table2', 'db2')->select();  // 查询第二个数据库中的表格数据
    }
}

In the above code, we query the table named table2 in the second database and store the results in $result middle. name() The method is used to specify the name of the table to be queried. The "db2" parameter indicates that the query is performed in the second database.

If you need to perform more complex query operations, you can also use the query constructor or query object provided by thinkphp.

So far, we have learned how to link two databases and perform query operations in the thinkphp framework. When dealing with multiple databases, it is recommended to standardize the configuration and usage as much as possible to avoid abnormal situations.

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