MySQL Connection

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MySQL Connection using mysql binary:

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

Example:

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

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

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

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.

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

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

mysql> exit
Bye

MySQL Connection using PHP Script:

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

Syntax:

connection mysql_connect(server,user,passwd,new_link,client_flag);
Parameter Description
serverOptional - The host name running database server. If not specified, then default value is localhost:3036.
userOptional - The username accessing the database. If not specified, then default is the name of the user that owns the server process.
passwdOptional - The password of the user accessing the database. If not specified, then default is an empty password.
new_linkOptional - If a second call is made to mysql_connect() with the same arguments, no new connection will be established; instead, the identifier of the already opened connection will be returned.
client_flagsOptional - A combination of the following constants:
  • MYSQL_CLIENT_SSL - Use SSL encryption

  • MYSQL_CLIENT_COMPRESS - Use compression protocol

  • MYSQL_CLIENT_IGNORE_SPACE - Allow space after function names

  • MYSQL_CLIENT_INTERACTIVE - Allow interactive timeout seconds of inactivity before closing the connection

You can disconnect from MySQL database anytime using another PHP function mysql_close(). This function takes a single parameter, which is a connection returned by mysql_connect() function.

Syntax:

bool mysql_close ( resource $link_identifier );

If a resource is not specified then last opened database is closed. This function returns true if it closes connection successfully otherwise it returns false.

Example:

Try out the following example to connect to a MySQL server:

<html>
<head>
<title>Connecting MySQL Server</title>
</head>
<body>
<?php
   $dbhost = 'localhost:3036';
   $dbuser = 'guest';
   $dbpass = 'guest123';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   if(! $conn )
   {
     die('Could not connect: ' . mysql_error());
   }
   echo 'Connected successfully';
   mysql_close($conn);
?>
</body>
</html>


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