How to query and return a one-dimensional array in php

PHP query returns one-dimensional array

In PHP development, it is very common to use MySQL database query. We often need to obtain the results of SQL queries for further processing. The query result can be a multi-dimensional array or a one-dimensional array. In this article, we will see how to get a one-dimensional array from a MySQL database query using PHP.

What is a one-dimensional array?

In PHP, arrays are a common data structure for storing data. A one-dimensional array is simply an array containing an index, which can store a single type of data (such as integers, strings, etc.).

How to query and return a one-dimensional array?

Querying and returning a one-dimensional array is very simple. We need to define a query statement to obtain the required data from the database, and then use the functions provided by the MySQL function library in PHP to execute the query and obtain the results. Here is some sample code:

<?php // 配置数据库信息
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test";

// 连接数据库
$conn = mysqli_connect($servername, $username, $password, $dbname);

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

// 定义查询语句
$sql = "SELECT username, email FROM users WHERE id=1";

// 执行查询语句，并将结果存储在 $result 中
$result = mysqli_query($conn, $sql);

// 将结果转换为一维数组
$row = mysqli_fetch_array($result, MYSQLI_ASSOC);

// 输出结果
echo "用户名：" . $row["username"] . "<br>";
echo "邮箱：" . $row["email"];

// 关闭连接
mysqli_close($conn);
?>

In the above example, we first defined the database connection parameters and then used the mysqli_connect() function to connect to the database. Next, we define a SQL query that will retrieve the username and email address of user id=1 from the users table. We execute the query using the mysqli_query() function and store the result in the $result variable.

Finally, we use the mysqli_fetch_array() function to convert the query results into a one-dimensional array and store the values ​​in the array in the $row variable. We can access the values ​​in this array by index, or we can use the keys of an associative array to get the values. In this example, I used $row["username"] and $row["email"] to get the values ​​of these two fields.

Conclusion

In this article, we learned how to use PHP to query data from a MySQL database and return a one-dimensional array. This is very simple, just use some functions and statements provided by the MySQL function library in PHP. Now you're ready to put these skills to use in your PHP development process!

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