How does the type of a PHP function return value match the type of a database query result?

Use the type conversion function to match the type of the PHP function return value and the type of the database query result, including: integer (intval()), floating point (floatval()), string (strval()), Boolean Values ​​(boolval()) and arrays (json_decode() or explode()).

How does the type of the PHP function return value match the type of the database query result?

Problem

When using PHP's database query function (such as mysqli_query()), you may encounter the problem of changing the query Compatibility issues between the result type and the return value type of PHP functions. This article will show you how to resolve this issue.

Solution

To match the type of the function return value, you can use a type conversion function. For example:

• Integer type (int): Use intval() function
• Floating point type (float): Use floatval() function
• String (string): Use strval() function
• Boolean value(boolean): Use boolval() Function
• Array(array): Use json_decode() or explode() Function

Practical case

Assume we have a database table named users, It contains two columns: id (integer) and username (string). Now, let's create a PHP function to query this table and match the type of the query result:

<?php

function getUser($id) {
  // 连接数据库
  $conn = new mysqli("localhost", "root", "password", "dbname");

  // 准备查询
  $sql = "SELECT * FROM users WHERE id = ?";

  // 创建预处理语句
  $stmt = $conn->prepare($sql);
  $stmt->bind_param("i", $id);

  // 执行查询
  $stmt->execute();

  // 获取结果
  $result = $stmt->get_result();

  // 将结果转换为 PHP 数组
  $user = $result->fetch_assoc();

  // 将 id 转换为整型
  $user['id'] = intval($user['id']);

  // 关闭语句和连接
  $stmt->close();
  $conn->close();

  // 返回用户数据
  return $user;
}

// 获取特定用户的 ID
$userId = 1;

// 调用 getUser() 函数并获取用户数据
$user = getUser($userId);

// 打印用户数据
echo "ID: {$user['id']}, Username: {$user['username']}";
?>

In the above example, we convert the result of the id column to an integer to match Return value type of PHP function getUser(). We can also transform other columns as needed.

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