How to import and export data through PHP and database

How to import and export data through PHP and database

Importing and exporting data is a common requirement in web development, especially when processing large amounts of data. As a commonly used server-side scripting language, PHP can be used in combination with a database to achieve fast and efficient data import and export functions. This article will introduce how to use PHP code to import and export data, and provide corresponding sample code.

1. Data export

Data export usually saves the data in the database in a local file in a certain format for future analysis and use. In PHP, we can export data through the following steps:

1. First, establish a connection with the database. Use PHP's database connection function (such as mysqli_connect()) to connect to the database and select the appropriate database.

Sample code:

<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检查连接是否成功
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

echo "连接成功";

// ...其他数据处理操作

// 关闭连接
mysqli_close($conn);
?>

2. Query the data and save the results to a local file. Use PHP's database query function (such as mysqli_query()) to execute the corresponding SQL query statement and save the query results to a local file. You can use PHP's file processing functions (such as fopen(), fwrite(), and fclose()) to create, write, and close files.

Sample code:

<?php
// ...建立数据库连接

// 执行查询语句
$sql = "SELECT * FROM mytable";
$result = mysqli_query($conn, $sql);

// 检查查询结果
if (mysqli_num_rows($result) > 0) {
    // 创建本地文件
    $filename = 'export_data.csv';
    $file = fopen($filename, 'w');

    // 写入表头
    $row = mysqli_fetch_assoc($result);
    fputcsv($file, array_keys($row));

    // 写入数据
    mysqli_data_seek($result, 0); // 将查询结果指针重置到起始位置
    while ($row = mysqli_fetch_assoc($result)) {
        fputcsv($file, $row);
    }

    // 关闭文件
    fclose($file);

    echo "数据导出成功";
} else {
    echo "没有数据";
}

// ...关闭数据库连接
?>

In the above code, use the mysqli_num_rows() function to determine whether the query result is empty. If not, create a local file and write the query result. header and data to the file, and finally close the file. Here we take CSV format as an example. You can choose the appropriate file format according to your needs.

2. Data import

Data import is to import data from local files into the database in batches. In PHP, data import can be achieved through the following steps:

1. Establish a connection with the database and select the appropriate database, which is the same as the previous data export.
2. Read the data in the local file and insert it into the database one by one. Use PHP's file processing functions (such as fopen(), fgetcsv(), and fclose()) to read the data in the local file line by line, and use the database's insert statement to insert the data into the database.

Sample code:

<?php
// ...建立数据库连接

// 打开本地文件
$file = fopen('import_data.csv', 'r');

// 检查文件是否打开成功
if ($file) {
    // 逐行读取数据
    while (($row = fgetcsv($file)) !== false) {
        // 执行插入语句
        $sql = "INSERT INTO mytable (column1, column2, column3) VALUES ('$row[0]', '$row[1]', '$row[2]')";
        if (mysqli_query($conn, $sql)) {
            echo "插入数据成功";
        } else {
            echo "插入数据失败";
        }
    }

    // 关闭文件
    fclose($file);
} else {
    echo "打开文件失败";
}

// ...关闭数据库连接
?>

In the above code, the fgetcsv() function is used to read the local file data in CSV format line by line, and then insert the data into the database according to the required insert statement. middle.

Summary:

Through the combination of PHP and database, we can easily realize the data import and export functions. Whether it is data analysis, backup or data exchange, it can all be completed through the above methods. In practical applications, appropriate methods and technologies can be selected based on specific needs and data formats.

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