PHP and PDO: How to import and export data from a database

PHP and PDO: How to import and export data in a database

Importing and exporting data in a database is a common task that can be used in different application scenarios. This article will introduce how to use PHP and PDO extensions to import and export database data, and provide corresponding code examples.

1. Export data in the database

To export data in the database, you first need to connect to the database and execute the corresponding query. Then, write the query results to the file to facilitate subsequent import operations. The following is a sample code:

<?php
// 连接到数据库
$dsn = 'mysql:host=localhost;dbname=test';
$username = 'root';
$password = '';

try {
    $pdo = new PDO($dsn, $username, $password);

    // 导出数据的查询语句，可以根据需要自行修改
    $query = 'SELECT * FROM users';

    // 执行查询
    $stmt = $pdo->query($query);

    // 将查询结果写入到文件中
    $filename = 'exported_data.csv';
    $fp = fopen($filename, 'w');

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        fputcsv($fp, $row);
    }

    fclose($fp);

    echo '数据导出成功！';
} catch (PDOException $e) {
    echo '数据库连接失败: ' . $e->getMessage();
}
?>

In the above code, we first create a PDO object and use it to execute the query statement. Then, loop through the query results and write each row of data to a file using the fputcsv function.

2. Import data in the database

To import data into the database, you first need to read the data from the file and parse it into an array. Then, insert the data in the array into the database one by one. The following is a sample code:

<?php
// 连接到数据库
$dsn = 'mysql:host=localhost;dbname=test';
$username = 'root';
$password = '';

try {
    $pdo = new PDO($dsn, $username, $password);

    // 读取导入的文件
    $filename = 'exported_data.csv';
    $fp = fopen($filename, 'r');

    // 解析CSV文件并逐条插入到数据库中
    while (($row = fgetcsv($fp)) !== false) {
        $stmt = $pdo->prepare('INSERT INTO users (name, email) VALUES (?, ?)');
        $stmt->execute($row);
    }

    fclose($fp);

    echo '数据导入成功！';
} catch (PDOException $e) {
    echo '数据库连接失败: ' . $e->getMessage();
}
?>

In the above code, we first create a PDO object and open the imported file through the fopen function. Then, each line of data in the file is read through a loop and parsed into an array using the fgetcsv function. Finally, the data in the array is inserted into the database through the prepare and execute methods.

Using the above code example, you can easily export data from the database to a file and import from the file into the database. This is very practical in scenarios such as data backup, migration and data analysis. At the same time, through the API provided by PDO extension, different database types can be easily processed, making the code more portable and compatible.

Summary: This article introduces how to use PHP and PDO extensions to import and export data in the database. By flexibly using PDO's API, we can easily read and write data and realize various database operation requirements. I hope this article will be helpful to your database operations in development.

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