Database Connection Mysql

Steps of using MySql db from Php.

1. Create a database connection.
2. Select a database.
3. Perform a SQL query.
4. Perform your operations on SQL query results.
5. Close database connection. 

1. Create a database connection.
Php uses following funtions for making a databse connection .
mysql_connec(server,user,pwd,newlink,clientflag) // Non persistance connection
mysql_pconnec(server,user,pwd,newlink,clientflag) // Persistance connection.

Parameter	Description
server	Optional. Hostname of server. Default value is "localhost:3306"
user	Optional. Username on the database. Default value is the name of the user that owns the server process
pwd	Optional. Username on the database. Default is ""
newlink	Optional. Reuse database connection created by previous call to mysql_connect
clientflag	Optional. Can be 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

2. Select a database.
Php use following function for selecting database.
mysql_select_db(database,connection)
   database -- Specifies the database to select.
   connection -- (Optiona)l. Specifies the MySQL connection. If not specified, the last connection opened by mysql_connect() or mysql_pconnect() is used.

3. Perform a SQL query.
Php have following function to executes a query on a MySQL database.
mysql_query(query,connection)
   query -- SQL query to execute (eg. SELECT query, UPDATE query...etc);
   connection -- (Optional) MySQL connection name. If not specified, the last connection opened by mysql_connect() or mysql_pconnect() is used.
This function returns the query handle for SELECT queries, TRUE/FALSE for other queries, or FALSE on failure.
4. Close database connection. 
Php uses following function for closing a connection.
mysql_close(connection) // function closes a non-persistent MySQL connection.

Sample Code :
<?php
$con = mysql_connect("server","username","password");
if (!$con)   {
  die('Unable to connect: ' . mysql_error());  
}else{
mysql_select_db('database_name');
}
$sql = "SELECT * FROM Customer";
mysql_query($sql,$con);
// do some more precessing ..
mysql_close($con);
?>