How to query MySQL using PHP and return an array

Before we start, we need to prepare some things:

• A Web server with PHP and MySQL installed

• A MySQL database with some data in it

• Know how to connect to a MySQL database

Now, let’s say we have all of this ready Materials, we can start using PHP to query MySQL and return an array.

First, we need to create a PHP script that connects to the MySQL database. Here we can use the mysqli class in PHP to establish the connection. The following is an example of establishing a connection:

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

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

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
} 
?>

We use four variables to represent the name of the MySQL server, user name, password and database name. We created a new connection object using the mysqli class and verified the success of the connection. If the connection fails, it will display a connection error message and exit the script.

We will use the SELECT statement to get data from the MySQL database. The following is an example of retrieving data from a table named "customers" using a SELECT statement:

<?php
$sql = "SELECT * FROM customers";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 将查询结果存储到数组中
    $data = array();
    while($row = $result->fetch_assoc()) {
        $data[] = $row;
    }
} else {
    echo "0 结果";
}
?>

We have used a SELECT statement to retrieve all data from a table named "customers". This is Operation of this example. We use the query() method to execute the query and verify that there are rows in the result set. If there are rows returned by the query, then we will store the results in an array called $data so that it can be used in the web application.

To store the query results, we use a while loop to iterate each row in the result set and add it to the data array.

Finally, we can use the $data array to present query results in a web application. For example, we can display the query results as an HTML table:

<table>
    <tr>
        <th>姓名</th>
        <th>地址</th>
        <th>城市</th>
        <th>电话号码</th>
    </tr>
    <?php foreach ($data as $row): ?>
        <tr>
            <td><?php echo $row[&#39;name&#39;]; ?></td>
            <td><?php echo $row[&#39;address&#39;]; ?></td>
            <td><?php echo $row[&#39;city&#39;]; ?></td>
            <td><?php echo $row[&#39;phone&#39;]; ?></td>
        </tr>
    <?php endforeach; ?>
</table>

We use a foreach loop to traverse each row in the $data array and display the data using an HTML table. When we access the data fields of each data row, we implement it in the $data array through an associative array.

In web applications, we can easily display data by querying MySQL with PHP and storing the results as an array. This makes our web application powerful and easy to maintain. In web development, querying MySQL with PHP and returning an array is a very practical technique.

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