Mysqli 简明教程

MySQLi - Connection

MySQL Connection Using MySQL Binary

你可以在命令提示符下使用 mysql 二进制文件建立 MySQL 数据库。

You can establish the MySQL database using the mysql binary at the command prompt.

Example

下面是一个从命令提示符连接到 MySQL 服务器的简单示例 −

Here is a simple example to connect to the MySQL server from the command prompt −

[root@host]# mysql -u root -p
Enter password:******

这会给你 MySQL 命令提示符,你可以在其中执行任何 SQL 命令。以下是上述命令的结果−

This will give you the mysqli command prompt where you will be able to execute any SQL command. Following is the result of above command −

以下代码块显示了以上代码的结果 −

The following code block shows the result of above code −

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2854760 to server version: 5.0.9

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

在上述示例中,我们使用了 root 作为用户,但你也可以使用任何其他用户。任何用户都可以执行所有被允许执行的 SQL 操作。

In the above example, we have used root as a user but you can use any other user as well. Any user will be able to perform all the SQL operations, which are allowed to that user.

你可以随时使用 mysql> 提示符下的 exit 命令断开 MySQL 数据库连接。

You can disconnect from the MySQL database any time using the exit command at mysql> prompt.

mysql> exit
Bye

MySQL Connection Using PHP Script

PHP 提供 mysqli 构造或 mysqli_connect() 函数来打开一个数据库连接。此函数采用六个参数,并且在成功时返回一个 MySQL 链接标识符,在失败时返回 FALSE。

PHP provides mysqli contruct or mysqli_connect() function to open a database connection. This function takes six parameters and returns a MySQL link identifier on success or FALSE on failure.

Syntax

$mysqli = new mysqli($host, $username, $passwd, $dbName, $port, $socket);

Sr.No.

Parameter & Description

1

$host Optional − The host name running the database server. If not specified, then the default value will be localhost:3306.

2

$username Optional − The username accessing the database. If not specified, then the default will be the name of the user that owns the server process.

3

$passwd Optional − The password of the user accessing the database. If not specified, then the default will be an empty password.

4

$dbName Optional − database name on which query is to be performed.

5

$port Optional − the port number to attempt to connect to the MySQL server..

6

$socket Optional − socket or named pipe that should be used.

你可以随时使用另一个 PHP 函数 close() 来断开 MySQL 数据库连接。

You can disconnect from the MySQL database anytime using another PHP function close().

Syntax

$mysqli→close();

Example

尝试以下示例以连接到 MySQL 服务器 −

Try the following example to connect to a MySQL server −

将以下示例复制粘贴为 mysql_example.php:

Copy and paste the following example as mysql_example.php −

<html>
   <head>
      <title>Connecting MySQL Server</title>
   </head>
   <body>
      <?php
         $dbhost = 'localhost';
         $dbuser = 'root';
         $dbpass = 'root@123';
         $mysqli = new mysqli($dbhost, $dbuser, $dbpass);

         if($mysqli→connect_errno ) {
            printf("Connect failed: %s<br />", $mysqli→connect_error);
            exit();
         }
         printf('Connected successfully.<br />');
         $mysqli→close();
      ?>
   </body>
</html>

Output

访问部署在 Apache Web 服务器上的 mysql_example.php, 并验证输出。

Access the mysql_example.php deployed on apache web server and verify the output.

Connected successfully.