How to use database adapter in PHP?

Database Adapter is a design pattern in PHP that allows applications to interact with a database independently from the underlying database system. Several database adapters are available in PHP, such as PDO, mysqli, and PDO_MySQL. To use a database adapter, you load the adapter library, create a database connection, execute queries, get results, and close the connection. In the example of using the PDO adapter to retrieve all records from the users table, the adapter allows the application to interact with the MySQL database without knowing its specific implementation details.

Database Adapter in PHP

What is a database adapter?

A database adapter is a design pattern that allows applications to interact with a database independently of the underlying database system. It does this by providing an abstraction layer that hides database-specific implementation details, such as data models and query syntax.

Database Adapter in PHP

PHP provides multiple database adapters, including:

• PDO (PHP Data Object)
• mysqli
• PDO_MySQL

How to use the database adapter

The following steps explain how to use the database adapter in PHP:

1. Load database adapter library

   For example, to use the PDO adapter:

   require_once 'PDO.php';

2. Create a database connection object

   Use the new keyword to create a connection object and pass in the required connection parameters:

   $conn = new PDO('mysql:host=localhost;dbname=my_database', 'root', 'password');

3. Execute the query

   Use the query() method to execute the query and obtain the result set:

   $stmt = $conn->query('SELECT * FROM my_table');

4. Get the results

   Use the fetch() or fetchAll() method to obtain query results:

   while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
       echo $row['name'];
   }

5. Close the connection

   After completion, use theclose() method to close the database connection:

   $conn->close();

Practical case

Suppose we have a database table named users which contains the name and age fields. The following example demonstrates how to use the PDO adapter to retrieve all records from a table:

query('SELECT * FROM users');

// 获取结果
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    echo $row['name'] . ' ' . $row['age'] . '
';
}

// 关闭连接
$conn->close();

?>

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