How to query data assignment array in php

In PHP, querying the database is a very common operation. The query results are often returned in the form of an array. For this reason, we need to assign the query results to an array variable for subsequent operations. This article explains how to query data in PHP and assign the results to an array.

1. Connect to the database

Before performing any database operations, we need to connect to the database first. The following is a simple example of connecting to a MySQL database:

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

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

// 检测连接
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}
echo "连接成功";
?>

In the above code, we first define some parameters required to connect to the MySQL database, including server name, user name, password, database name, etc. Then use the mysqli_connect() function to create a connection object $conn. This function needs to pass in $servername, $username, ## Parameters such as #$password and $dbname. Finally, we determine if the connection was successful by checking if $conn is false.

Query data

After the database connection is successful, we can query the data. The following is a simple example of querying the MySQL database:

<?php
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 输出每行数据
    while($row = mysqli_fetch_assoc($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}

mysqli_close($conn);
?>

In the above code, we first define the

$sql variable to save the query statement. Then use the mysqli_query() function to execute the $sql statement. This function needs to pass in the connection object $conn and the query statement $sql parameters.

If the query is successful, the

mysqli_query() function will return a result set $result, which contains all the queried data. We can get each row of data in a way similar to array subscripting. mysqli_fetch_assoc() The function can fetch a row of data from the result set $result and return it to the variable $row as an associative array. mysqli_num_rows() Function is used to get the number of rows in the result set.

Finally, we use the

mysqli_close() function to close the connection.

Assign a value to an array

After querying the database and obtaining the results, we can assign the results to an array. The following is a simple example of assigning query results to an array:

<?php
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = mysqli_query($conn, $sql);

$myArray = array(); // 定义一个空数组

if (mysqli_num_rows($result) > 0) {
    // 输出每行数据
    while($row = mysqli_fetch_assoc($result)) {
        $myArray[] = $row; // 将关联数组 $row 添加到数组 $myArray 中
    }
} else {
    echo "0 结果";
}

mysqli_close($conn);

print_r($myArray); // 输出数组
?>

In the above code, we first define an empty array

$myArray. Then in the loop, each time the $row associative array is added to the $myArray array, i.e. $myArray[] = $row;. Finally, we can use the print_r() function to output the array $myArray to the page.

Through the above examples, we learned how to query the database in PHP and assign the results to an array. This is also one of the basic skills necessary for PHP programmers. Hope this article can be helpful to beginners.

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