How to use array traversal to query the database in php

Nowadays, with the rapid development of the Internet and information technology, more and more websites and applications need to use databases for data storage and management. In the data operation process, PHP, as a popular server-side scripting language, is very convenient for processing data. This article will introduce how to use array traversal to query the database in PHP.

In PHP, we can use arrays to organize data and improve data readability and scalability. At the same time, we often need to get data from the database and convert it into an array, which raises a question: How to traverse the array to query the database?

First, we need to use PHP's database extension to connect to the database and perform query operations. In this example, we will use MySQL as the database and use the mysqli extension to connect to the database. Here is the PHP code to connect to the database:

// 数据库连接参数
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

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

// 检查连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
echo "连接成功";

Next, we need to perform the query operation and store the results into an array. In this example, we will get the data from the "customers" database table and use a while loop to store each result into an array. The PHP code is as follows:

$sql = "SELECT id, firstname, lastname, email FROM customers";
$result = $conn->query($sql);

$customers = array();

if ($result->num_rows > 0) {
    // 输出每行数据
    while($row = $result->fetch_assoc()) {
        $customer = array(
            'id' => $row['id'],
            'firstname' => $row['firstname'],
            'lastname' => $row['lastname'],
            'email' => $row['email']
        );
        array_push($customers, $customer);
    }
} else {
    echo "0 结果";
}

In the above code, we first define an empty array $customers to store the result set. We then execute the query and store the result set in the $result variable. Next, we use a while loop to iterate through the result set, store each result in the $customer array, and add the $customer array to the $customers array.

Finally, we can use a foreach loop to traverse the $customers array to obtain the information of each customer. The PHP code is as follows:

foreach ($customers as $customer) {
    echo "ID：" . $customer['id'] . "<br>";
    echo "姓名：" . $customer['firstname'] . " " . $customer['lastname'] . "<br>";
    echo "邮箱：" . $customer['email'] . "<br><br>";
}

In the above code, we use a foreach loop to traverse the $customers array and output the ID, name and email information of each customer.

To sum up, using array traversal to query the database in PHP can help us better manage and operate data. With the above code, we can better understand how to connect to the database, perform query operations, and convert the results into an array. At the same time, we also learned how to traverse the array and obtain the information of each customer. These techniques are very useful in practical applications. I hope this article can be helpful to everyone.

The above is the detailed content of How to use array traversal to query the database in php. For more information, please follow other related articles on the PHP Chinese website!