DBAR in Yii framework: using databases more simply

Yii framework is an excellent PHP framework and has become one of the first choices for many web developers. Among them, the database is one of the very important components for web applications. In the Yii framework, DBAR is a component that encapsulates database query operations. Through it, we can use the database more simply.

DBAR refers to "Database Access Object". First of all, it is a component that encapsulates database queries in the Yii framework. Secondly, it separates query conditions and query results, and uses chain programming to construct query statements. Finally, DBAR can also be used to build queries in a SQL-like manner.

To use DBAR for data query, you need to first configure the database connection parameters through the component configuration file of the Yii framework (for example: main.php). Let's take a look at how to configure it:

return [
    // ...
    'components' => [
        'db' => [
            'class' => 'yiidbConnection',
            'dsn' => 'mysql:host=localhost;dbname=mydatabase',
            'username' => 'root',
            'password' => '',
            'charset' => 'utf8',
        ],
        'db2' => [
            'class' => 'yiidbConnection',
            'dsn' => 'mysql:host=localhost;dbname=mydatabase2',
            'username' => 'root',
            'password' => '',
            'charset' => 'utf8',
        ],
        // ...
    ],
];

The above code shows how to configure the database connection parameters in the Yii framework. Please note that here we can configure multiple database connection parameters, each database connection has an independent name, so that you can choose the database connection to use during operation.

When we use Yii's DBAR component to access the database, we can obtain the database connection through Yii::$app->db or Yii::$app->get('db'). We can use DBAR to perform select, update, insert, delete and other operations.

Regarding the select operation, we can perform a simple query through the following code:

$posts = Yii::$app->db->createCommand('SELECT * FROM posts')->queryAll();

DBAR also supports the use of chain programming to build query statements, for example:

$posts = Yii::$app->db->createCommand()
    ->select('title, content')
    ->from('posts')
    ->where(['status' => 1])
    ->orderBy('id DESC')
    ->limit(10)
    ->queryAll();

In the above code, we use the query builder createCommand() method, and call the select(), from(), where(), orderBy() and limit() methods in a chain. This allows you to construct very simple queries.

The insert and update operations can be performed using the following code:

Yii::$app->db->createCommand()->insert('user', [
    'name' => 'user1',
])->execute();

Yii::$app->db->createCommand()->update('user', [
    'name' => 'user2',
], 'age > 20')->execute();

The delete operation can be performed using the following code:

Yii::$app->db->createCommand()->delete('user', 'age > 20')->execute();

The DBAR in the Yii framework makes it more convenient for us It is very convenient to use the database efficiently, especially when building simple query statements. At the same time, you can also use chain programming to build more complex query statements. In short, DBAR is a very powerful and easy-to-use component. If you are developing a Yii framework web application and interacting with the database, please be sure to try using DBAR for data operations. I believe you will fall in love with it!

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