What is the method for connecting and operating database in PHP?

In the current Internet era, data storage and management is a crucial part. As a programming language widely used in web development, PHP has powerful database connection and operation functions, and can interact with the database conveniently and flexibly. This article will introduce how to connect and operate databases in PHP.

First of all, we need to understand that PHP's database connection is implemented through extensions. Currently, the most commonly used PHP database extensions are MySQLi (MySQL Improved) and PDO (PHP Data Objects). This article will use MySQLi as an example to explain.

Step 1: Establish a database connection

In PHP, you can connect to the MySQL database through the mysqli_connect() function. This function accepts four parameters, namely database host name, user name, password and database name. Here is an example:

$conn = mysqli_connect("localhost", "root", "password", "database");

This code will try to connect to the MySQL database named "database", which is located on the local host, and use "root" as the username and "password" as the password.

Step 2: Execute SQL query

After successfully connecting to the database, we can use the mysqli_query() function to execute the SQL query statement. This function accepts two parameters, which are the database connection object and the SQL statement to be executed. The following is an example:

$result = mysqli_query($conn, "SELECT * FROM table");

This code will execute a SELECT query statement to retrieve the values ​​of all columns from the table named "table".

Step 3: Process the query results

After executing the query through the mysqli_query() function, you can obtain the query results row by row through the mysqli_fetch_array() function. This function accepts one parameter, which is the query result object to be processed. Here is an example:

while ($row = mysqli_fetch_array($result)) {
    echo $row['column'];
}

This code will get each row in the query results row by row and output the value of the column named "column".

Step 4: Close the database connection

When the database operation is completed, we should close the database connection through the mysqli_close() function to release resources. This function accepts one parameter, the database connection object. The following is an example:

mysqli_close($conn);

This code will close the previously established database connection.

In summary, through the above steps, we can simply understand how PHP performs database connections and operations. Of course, this is only a very basic operation, and actual applications will also involve more complex database operations, such as adding, modifying, and deleting data. In addition, PDO is also a commonly used database extension, and its usage is similar to MySQLi. Through learning and practice, we can become more proficient in PHP's database connection and operation skills, laying the foundation for implementing more complex web applications.

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