To establish a connection with a MySQL server, a data source name (DSN) is created in which connection parameters are specified, and also the UserName and Password of your MySQL account is also used.

$db = new PDO("DSN", "Username", "Password"); where, DSN = Data Source Name(DSN) is a string of multiple arguments that indicates the database driver(esp. mysql), a hostname, in which the server actually is processed and the name of the database to whom we have to connect. Syntax:- mysql:host=host_name;dbname=db_name
Username = Username of the database
Password = Password of the database
Eg :-
$db = new PDO( "mysql:host=localhost;dbname=testing" , "test_user" , "test_pass" );

Closing the Connection
When you are finished using the connection, simply close it by setting the database handler to NULL …show more content…
PHP will throw an exception, if “new PDO()” constructor fails. The returned object from the constructor method is a database handler used for interacting with the server till the end of the connection.
When the database handler is open and you are using it to issue other PDO calls, you should arrange to handle error if they occur.
If you enable exception, you also have the option of catching them yourself instead of permitting them to print a backtrace and terminating the script.
To enable exceptions, set the PDO error mode as follows after connecting for checking for an error after each PDO