resource mysql_connect ( [string server [, string username [, string password 

[, bool new_link [, int client_flags]]]]])

Another way to connect to a MySQL server is to use the 

mysql_pconnect()

function, which acts very much like 

mysql_connect()

 with two major differences: 

When connecting the first time, the function would try to find a (persistent) link 

that is already open with the same host, username and password. If one is 

found, an identifier for it will be returned instead of opening a new connection. 

The connection to the MySQL server will not be closed when the execution of 

the script ends. Instead, the link will remain open for future use.

The

 server

 variable in the 

mysql_connect()

 function contains the hostname or 

the IP address of the server that provides the MySQL database.

Choosing the MySQL database is done by the mysql_select_db() function:

bool mysql_select_db ( string database_name [, resource link_identifier])

The connection part of our sample application using MySQL database is shown 

in Example 7 22.

Example 7 22   Connecting a MySQL database

$db_host   = "localhost";

$db_user   = "itsosj";

$db_pass   = "itsosj";

$datab     = "itsodb";

$db = mysql_connect($db_host,$db_user,$db_pass) 

or die("Could not connect ".

mysql_error());

mysql_select_db($datab,$db) or die(mysql_error());

When connecting a DB2 database with ODBC, the connection is done in a single 

ODBC command (

odbc_connect()

).

resource odbc_connect ( string dsn, string user, string password [, int 

cursor_type])

Note:

 As we use the IBM DB2 native driver, the DSN is the database name 

which is registered in the DB2 catalog. Therefore, no server address has to be 

declared in the connect statement.

The migrated connection part of the sample application is shown in 

Example 7 23. In our connection script snippet, the statement after connection 

statement sets the current schema, which will be used when querying the 

 Chapter 7. Application porting 

179