A brief analysis of how PHP operates the database

The database is an important part of network programming. It is used to store and manage large amounts of data. In network applications, user information, product information and other data information need to be stored and managed, so database operation is an essential part of developing a website. As a widely used back-end server programming language, PHP also provides us with a series of database operation functions, allowing us to easily add, delete, and modify the database.

This article will briefly introduce the commonly used database addition, deletion and modification operations in PHP, including SQL statements, PDO classes and MySQLi classes. I hope that the introduction in this article can help developers better understand the operation of databases under PHP.

1. SQL statement

SQL statement is a general query language in the database, which is used to operate the database through statements to complete the addition, deletion and modification of data. , check and other operations. To operate the database through SQL statements in PHP, you can use the mysql_query() function, mysqli_query() function, and PDO preprocessing statements.

1.mysql_query() function

The mysql_query() function is a function used to execute SQL statements in PHP. To use this function, you need to connect to MySQL data, and then pass in SQL statements through this function to operate on the data. For example, insert data using the INSERT command:

<?php $con = mysql_connect("localhost","root","password");
mysql_select_db("my_db", $con);
mysql_query("INSERT INTO Persons (FirstName, LastName, Age) 
VALUES (&#39;Peter&#39;, &#39;Griffin&#39;, &#39;35&#39;)");
mysql_close($con);
?>

2.mysqli_query() function

mysqli_query() function is a function in PHP for SQL statements with parameter bindings. Unlike the mysql_query() function, the mysqli_query() function supports SQL statements with parameter bindings. For example, inserting data using the INSERT command can be written as:

<?php $mysqli = new mysqli("localhost", "root", "password", "my_db");
$stmt = $mysqli->prepare("INSERT INTO Persons (FirstName, LastName, Age) VALUES (?, ?, ?)");
$stmt->bind_param("ssi", $fname, $lname, $age);
$fname = "Peter";
$lname = "Griffin";
$age = 35;
$stmt->execute();
$stmt->close();
$mysqli->close();
?>

3.PDO prepared statement

PDO (PHP Data Objects) is a PHP extension that can be used to access and operate different types of Databases, including MySQL, Oracle and SQL Server, etc. Through PDO prepared statements, we can execute SQL statements based on the parameters passed in. For example, to insert data, use the INSERT command:

<?php $pdo = new PDO("mysql:host=localhost;port=3306;dbname=my_db", "root", "password");
$statement = $pdo->prepare("INSERT INTO Persons (FirstName, LastName, Age) VALUES (:fname, :lname, :age)");
$statement->bindParam(':fname', $fname);
$statement->bindParam(':lname', $lname);
$statement->bindParam(':age', $age);
$fname = "Peter";
$lname = "Griffin";
$age = 35;
$statement->execute();
$pdo = null;
?>

2. PDO class

The PDO class is a package in PHP used to interact with the database. To connect to the database through the PDO class, we can use the prepare() method to create a prepared statement, add parameters to the SQL statement, and then provide the SQL statement and data to the execute() method. The PDO class also provides methods such as beginTransaction() and commit() for opening and submitting transactions.

<?php $pdo = new PDO("mysql:host=localhost;port=3306;dbname=my_db", "root", "password");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->beginTransaction();
try {
    $statement = $pdo->prepare("INSERT INTO Persons (FirstName, LastName, Age) VALUES (?, ?, ?)");
    $statement->bindParam(1, $fname);
    $statement->bindParam(2, $lname);
    $statement->bindParam(3, $age);
    $fname = "Peter";
    $lname = "Griffin";
    $age = 35;
    $statement->execute();
    $pdo->commit();
}
catch(PDOException $e) {
    $pdo->rollback();
    echo "Error: " . $e->getMessage();
}
$pdo = null;
?>

3. MySQLi class

The MySQLi class is an extension library for using MySQL in PHP. The functions it provides are more powerful and safer than the mysql_* function. It supports New MySQL server features such as transactions and stored procedures. To use the MySQLi class, you need to create an instance of the mysqli class through the new keyword, and then call the connect() method to connect to the MySQL server.

<?php $mysqli = new mysqli("localhost", "root", "password", "my_db");
$mysqli->query("INSERT INTO Persons (FirstName, LastName, Age) VALUES ('Peter', 'Griffin', '35')");
$mysqli->close();
?>

Summary

This article mainly introduces the common database addition, deletion and modification operations in PHP, including SQL statements, PDO classes and MySQLi classes. Through the introduction of this article, we can learn about different operation methods and their advantages and disadvantages, and also note the role of parameter binding in security. Of course, in actual development, it is also necessary to use the most appropriate way to operate the database according to project needs to maximize user needs.

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