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This article will explain in detail how to connect to the MySQL database in PHP. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

What is a MySQL database?

MySQL is a secure, cross-platform, efficient, and closely integrated database system with multiple programming languages. MySQL is a database system used on Web that runs on a server. Because of its small size, high speed and low total cost of ownership, MySQL database can be called one of the fastest SQL language databases at present. In addition to having functions that many other databases do not have, MySQL database is a completely free product, and users can download MySQL database directly through the network without paying any fee. If you are interested, you can also click on "MySQL's latest manual tutorial" to learn.

The characteristics of MySQL Database

Powerful, cross-platform MySQL is suitable for different applications. MySQL supports at least 20 development platforms, which makes programs written on any platform portable without any changes to the program.

High running speed and high speed are the remarkable characteristics of MySQL. In MySQL, connections can be made very quickly; the SQL function is implemented using a highly optimized class library and runs extremely fast.

Support object-oriented, PHP support mixed programming. Programming methods can be divided into three ways: pure object-oriented, pure process-oriented, and the mixture of sentence object and process-oriented.

High security, flexible and secure permissions and password system.

Low cost, MySQL database is a completely free product, users can download directly through the Internet.

Support a variety of development languages, MySQL provides support for a variety of popular programming languages, providing them with a lot of API functions.

The database has a large storage capacity and supports powerful built-in functions. PHP provides a large number of built-in functions, covering almost all the functions in Web application development.

Application of database

Database is a system specially used to manage data resources. in fact, data is the objects that computers need to deal with every day, whether it is text, graphics, sound and so on. In the document management method, there are some problems, such as inconvenient transplantation, waste of storage space and so on, but the database is better enough to solve these problems.

The database is based on the management of the data itself, he saves all the data to the database, organizes it in an orderly manner, and makes it more convenient to use the data in the database with the help of the database management system. It can be understood that the database is the data collated by the computer, and the software that manages these data is the data management system. A database system is composed of a database and a data management system.

Multiple databases can be created in the same MySQL database server, and if each database is treated as a "repository", then the content data in the site is stored in this warehouse. The access and maintenance of data in the database are managed by database management system software.

Connect to MySQL database

Using PHP to operate MySQL database is one of the inevitable requirements for Web development. PHP provides complete functions for operating MySQL database, including all aspects from connecting to the database, executing SQL statements, dealing with data result sets, and closing the database. Through these functions, Web development based on MySQL database is efficient and simple. So let's take a look at how PHP connects to the MySQL database.

Before connecting to the database, make sure that the mysqli extension in PHP is turned on. To open the mysqli extension is to remove the comment extension=mysqli from the php.ini configuration file. We can check the phpinfo () function to see if the mysqli extension is enabled successfully:

Appears in the output:

It means that the mysqli extension in PHP has been enabled. After we confirm that it has been successfully enabled, we can use the mysqli_connect () function in the extension to connect PHP to the MySQL database.

The syntax format of the mysqli_connect () function is as follows:

Mysqli_connect ([string $host = ini_get ("mysqli.default_host") [, string $username = ini_get ("mysqli.default_user") [, string $password = ini_get ("mysqli.default_pw") [, string $dbname = "[, int $port = ini_get (" mysqli.default_port ") [, string $socket = ini_get (" mysqli.default_socket ")])

Among them, it should be noted that:

$host is an optional parameter for the server to connect to

$username is an optional parameter, and the MySQL user name used to log in

$password is an optional parameter and the password used to log in

$dbname is an optional parameter, which is the default database used when executing the query

$port is an optional parameter that specifies the port number to connect to the MySQL server

$socket is an optional parameter that specifies socket or named pipe to be used

The mysqli_connect () function is an alias for the mysqli::__construct () function, and you can also connect to the database using the object mysqli ().

Next, let's take a look at how to connect through an example, as follows:

The output will get the character set you set in the database. If you are not connected, the output results are as follows:

The above example is a process-oriented approach. Let's take a look at the object-oriented approach:

The output is consistent with the output in the example above.

If you want to close the connection, in general, the connection will be closed automatically after the script has been run. Of course, you can also use code to close the connection. The example is as follows:

$conn- > close ()

The above is the closing connection code for the object-oriented method. Let's take a look at the code for the process-oriented method. The example is as follows:

Mysqli_close ($conn); this is the end of the article on "how to connect to the MySQL database in PHP". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it out for more people to see.

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