Use the mysql_connect() function to connect to the database (PHP method 1 for operating MySQL database)-Mysql Tutorial-php.cn

Use the mysql_connect() function to connect to the database (PHP method 1 for operating MySQL database)

黄舟

Release： 2017-04-20 13:49:23

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How to operate MySQL database with PHP - use the mysql_connect() function to connect to mysql

##PHP provides a large number of MySQL database functions to facilitate the operation of the MySQL database Operation makes the development of web programs simpler and more flexible.

In the previous article "

Detailed explanation of the five steps of PHP accessing the MYSQL database (picture)", the steps for PHP to access the database were introduced. In this article we will introduce PHP to operate the database. Methods!

Use the mysql_connect() function to connect to mysql

To operate the MySQL database, you must first establish a connection with the MySQL server. The syntax format for connecting to the MySQL server As follows:

mysql_connect(&#39;hostname&#39;,&#39;username&#39;,&#39;password&#39;);

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Use the mysql_connect() function to connect to the database (PHP method 1 for operating MySQL database)

The return value of this function indicates this database connection. If the connection is successful, the function returns a resource to prepare for subsequent execution of SQL instructions.

The following example uses the mysql_connect() function to create a connection with MySQL locally. The specific example code is as follows:

<?php
header("Content-Type:text/html; charset=utf-8");
$link = mysql_connect("localhost","root","root")or die("不能连接到数据库服务器！".mysql_error()); //连接MySQL 服务器
if($link){
    echo "连接数据库成功"; 
}
?>

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The output result is:

Use the mysql_connect() function to connect to the database (PHP method 1 for operating MySQL database)

Note:

If you close the MySQL server, a prompt message will be output:

Can't connect to MySQL server on "localhost"(10061)

In the above code, use the mysql_connect() function to connect to the MySQL database server. As you can see from this function, you can Specify a non-local machine name as the database server, which ensures the off-site storage of data and the security isolation of the database.

External user Wangwang has direct access rights to the WWW server. If the database system is placed directly on the WWW server, it will bring security risks to the MySQL database. If a firewall is installed for the database system, then PHP can access the database through the LAN, and the computers inside the LAN are invisible to the outside. This ensures that the database is not attacked by outsiders.

In order to facilitate querying errors that occur due to connection problems, it is best to add an error shielding mechanism performed by the die() function. The above example uses the mysql_error() function to extract the error text of the MySQL function. If there is no error , an empty string is returned. If the browser displays the words "Warning: mysql_connect()...", it means that the database connection is wrong, so that the error location can be quickly discovered and corrected in time.

Tips:

#In website development, errors are inevitable. Developers should try their best to avoid errors and make them in a timely manner. It is also necessary to accurately find the cause of the error, which requires constant accumulation of experience!

Mysql_connect() function connects to the database. We will introduce it here. Below we will introduce how to select a database file. For details, please read "P

Using the mysql_select_db() function to select a database file (PHP Method 2 of operating MySQL database)》!

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