Database-related data types and their operation examples in PHP

Database-related data types in PHP and their operation examples

1. Introduction
The database is one of the most important components of the application. It is responsible for storing and managing the data required by the application. . In PHP, we can use a variety of methods to operate databases, such as MySQL, SQLite, Oracle, etc. This article will focus on commonly used database-related data types in PHP and their operation examples.

2. Data type

1. String (String)
   String is one of the most common data types and is used to store text data. In PHP, we can use strings to store usernames, passwords, article content, etc.

Sample code:

$username = 'John';
$password = '12345';
$content = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.';

2. Integer (Integer)
   Integers are used to store numbers without decimal parts. In PHP, integer types are usually used to store user ID, age and other data.

Sample code:

$user_id = 1;
$age = 25;

3. Floating point number (Float)
   Floating point number is used to store numbers with decimal parts. In PHP, we can use floating point number types to store data such as prices, coordinates, etc.

Sample code:

$price = 9.99;
$latitude = 37.7749;
$longitude = -122.4194;

4. Boolean value (Boolean)
   Boolean value is used to store true or false values. In PHP, we can use Boolean values ​​to represent the user's login status, purchase status, etc.

Sample code:

$is_logged_in = true;
$is_purchased = false;

5. Array (Array)
   Arrays are used to store multiple values ​​and are accessed in the form of indexes or key-value pairs. In PHP, we can use arrays to store multiple user information, product lists, etc.

Sample code:

$users = array('John', 'Mary', 'Tom');
$products = array('Apple' => 2.99, 'Banana' => 1.99, 'Orange' => 3.99);

6. Object (Object)
   Object is used to store a collection of multiple properties and methods. In PHP, we can use objects to represent entities such as users and products.

Sample code:

class User {
    public $name;
    public $email;
  
    public function __construct($name, $email) {
        $this->name = $name;
        $this->email = $email;
    }
}

$user = new User('John', 'john@example.com');

3. Data operation

1. Connect to the database
   To operate the database, you first need to connect to the database.

Sample code:

$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "my_database";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("连接数据库失败：" . $conn->connect_error);
}

2. Insert data
   Inserting data into a database table is a common operation.

Sample code:

$sql = "INSERT INTO users (name, email) VALUES ('John', 'john@example.com')";

if ($conn->query($sql) === TRUE) {
    echo "数据插入成功";
} else {
    echo "数据插入失败：" . $conn->error;
}

3. Querying data
   Querying data from the database is a frequent operation.

Sample code:

$sql = "SELECT * FROM users";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "姓名：" . $row['name'] . "，邮箱：" . $row['email'] . "<br>";
    }
} else {
    echo "没有查询到数据";
}

4. Update data
   Updating data in a database table is a common operation.

Sample code:

$sql = "UPDATE users SET name = 'Mary' WHERE id = 1";

if ($conn->query($sql) === TRUE) {
    echo "数据更新成功";
} else {
    echo "数据更新失败：" . $conn->error;
}

5. Delete data
   Deleting data from a database table is a common operation.

Sample code:

$sql = "DELETE FROM users WHERE id = 1";

if ($conn->query($sql) === TRUE) {
    echo "数据删除成功";
} else {
    echo "数据删除失败：" . $conn->error;
}

IV. Summary
This article introduces common database-related data types in PHP and their operation examples. In actual development, appropriate data types are selected according to specific needs, and corresponding operation methods are used to add, delete, modify, and query the database to meet the needs of the application. Mastering database operations is an indispensable and important skill for PHP development.

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