How to connect to database using PHP built-in functions?

This article describes the steps to connect to a MySQL database using PHP's built-in mysqli_* functions: Load the MySQL extension. To establish a connection, a hostname, username, password, database name and port are required. Check if the connection is successful. Practical case: Connect to the database named "test_db", the user name is "root", the password is empty, and the host name is "localhost". Close the connection.

Connect to the database using PHP built-in functions

PHP provides a variety of built-in functions to connect to different types of databases. This article will demonstrate how to use the mysqli_* function to connect to a MySQL database.

Prerequisites

• PHP is installed on your system.
• MySQL database has been created and configured.

Steps

1. Load MySQL extension

   Useextension=mysqli directive loads the MySQL extension into your php.ini configuration file.

2. Establish a connection

   Call the mysqli_connect() function to establish a connection to the database. This function requires five parameters:

   $mysqli = mysqli_connect($host, $username, $password, $database, $port);

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   • $host: The host name or IP address of the database server
   • $username: Use User name used to connect to the database
   • $password: Password used to connect to the database
   • $database: Name of the database to be connected
   • $port: The port the database server listens on (default is 3306)

3. Check the connection

   Use the mysqli_connect_errno() and mysqli_connect_error() functions to check whether the connection is successful.

   if (mysqli_connect_errno()) {
       echo "连接失败: " . mysqli_connect_error();
   }

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Practical case

Connect to a database named "test_db", the user name is "root", the password is empty, the host Named "localhost".

$mysqli = mysqli_connect("localhost", "root", "", "test_db");
if (mysqli_connect_errno()) {
    echo "连接失败: " . mysqli_connect_error();
}

Close the connection

Use the mysqli_close() function to close the connection.

mysqli_close($mysqli);

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