Using mysqli_fetch_assoc to Retrieve Rows as Associative Arrays in PHP

In PHP, interacting with a database is a common task; when we run a SELECT query and obtain a result set, we usually need to store the data in a PHP array for further processing.

PHP provides several functions for handling result sets, and a frequently used one is mysqli_fetch_assoc, which retrieves a row from the result set as an associative array, allowing access to data by column name.

The following example demonstrates how to use mysqli_fetch_assoc to fetch a row from a result set:

<?php
// Connect to database
$mysqli = new mysqli("localhost", "username", "password", "database");

// Check connection
if ($mysqli->connect_errno) {
    echo "连接数据库失败：" . $mysqli->connect_error;
    exit();
}

// Execute SELECT query
$result = $mysqli->query("SELECT * FROM users");

// Check if data returned
if ($result->num_rows > 0) {
    // Fetch one row as associative array
    $row = mysqli_fetch_assoc($result);

    // Output values
    echo "ID: " . $row['id'] . "<br>";
    echo "姓名: " . $row['name'] . "<br>";
    echo "年龄: " . $row['age'] . "<br>";
} else {
    echo "没有查询到数据。";
}

// Close connection
$mysqli->close();
?>

In the example, we first connect to the database using new mysqli and check the connection. Then we execute a SELECT query, storing the result in $result. We then call mysqli_fetch_assoc to fetch a row into $row and output its fields by name.

Note that mysqli_fetch_assoc returns the next row each time it is called and returns null when no more rows are available; to fetch multiple rows, call it repeatedly inside a loop.

Using mysqli_fetch_assoc makes it convenient to retrieve rows as associative arrays, improving code readability and maintainability when processing query results.

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