Getting started with PHP PDO: a powerful tool for easily mastering database operations

php editor Baicao will help you easily master the database operation tool-PHP PDO. As a database operation extension of PHP, PDO provides a convenient and safe way to connect and operate various databases. Through this article, you will learn how to use PDO to perform database queries, inserts, updates, and delete operations, allowing you to handle database interactions more efficiently and flexibly during the development process, and inject more possibilities into your projects.

First, you need to ensure that your PHPenvironment has the PDO extension library installed. Normally, php will install the PDO extension library by default, but if you are not sure whether the extension library is installed, you can use the following command to check:

php -m | grep pdo

If the command output contains the word "PDO", it means that the PDO extension library has been installed, otherwise you need to install the extension library manually.

2. Connect Database

After installing the PDO extension library, you can start connecting to the target database . The following is a code example to connect to the Mysql database:

$dsn = "mysql:host=localhost;dbname=my_database";
$username = "root";
$passWord = "password";

try {
$conn = new PDO($dsn, $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTioN);
} catch (PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}

In the above code, the $dsn variable contains the database connection information, including host name, database name, user name and password. After the connection is successful, a PDO object ($conn) will be created and the error handling mode will be set to PDO::ERRMODE_EXCEPTION, so that any error will throw an exception.

3. Execute query and obtain data

After connecting to the database, you can start executing queries and obtaining data. PDO provides a variety of methods to execute queries, the most commonly used method is to use the PDOStatement object.

$stmt = $conn->prepare("SELECT * FROM users");
$stmt->execute();
$results = $stmt->fetchAll();

foreach ($results as $row) {
echo "ID: " . $row["id"] . ", Name: " . $row["name"] . "<br>";
}

In the above code, the prepare() method is used to prepare a sql statement, the execute() method is used to execute the SQL statement, the fetchAll() method is used to obtain all query results, and finally a foreach loop is used to iterate through the results and output them.

4. Use prepared statements to prevent SQL injection

PDO also supports prepared statements, which can help prevent SQL injection attacks. The following is a code example using prepared statements:

$stmt = $conn->prepare("SELECT * FROM users WHERE name = ?");
$stmt->execute([$name]);
$results = $stmt->fetchAll();

In the above code, the prepare() method is used to prepare a SQL statement, but it is not executed directly. An array is passed in to the execute() method, which contains the actual value to replace the question mark (?). This effectively prevents SQL injection attacks because the actual values ​​are not inserted directly into the SQL statement.

5. Close the connection

After completing all database operations, remember to close the database connection to release resources and improve performance. You can use the close() method to close the connection:

$conn->close();

Summarize:

PHP PDO is a powerful tool that can help you easily access and operate various types of databases. This article introduces the basic usage of PDO, including connecting to the database, executing queries, obtaining data, and preventing SQL injection. With this knowledge, you can easily perform database operations and build more powerful PHP applications.

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