7.2.1  Converting MySQL Perl applications to DB2 UDB

Two interfaces between Perl and the MySQL database have to be considered 

when discussing application porting form MySQL to DB2. First is 

Mysql.pm

, a 

custom interface that works only with MySQL. The other newer interface is a 

plug in for the Database Independent (DBI) set of modules. DBI provides a 

common Perl API for all database accesses and enables greater portability. The 

DBI interface is the most robust and standard. However, many legacy systems 

still use the Mysql.pm interface to connect to MySQL. In fact, the MySQL 

interface Mysql.pm is currently implemented as an emulation on top of the DBI 

drivers. The interface for accessing DB2 is the DBI interface with the DBD::DB2 

driver. Information about and how to install the DBI interface and the DBD::DB2 

driver can be found at the following Web sites:

http://www.ibm.com/software/data/db2/perl/

http://www.perl.com/CPAN/modules/by module/DBD/

http://aspn.activestate.com/ASPN/Modules/

As applications using the DBI interface to connect to MySQL generally can be 

adapted to DB2 by simply changing the database driver from 

DBD::Mysql

 to 

DBD::DB2

; this section only discusses the application conversion from Mysql.pm 

to DBI interface.

Converting Mysql.pm to DBI interface supported code

The interface documentation is normally installed with the appropriate module in 

the 

perl 

directory. More detailed information about the interface and the provided 

functions can be found there.

Connecting database

With Mysql.pm, five different connect statements can be used to connect to a 

database in a MySQL server:

$dbh = Mysql >Connect;

$dbh = Mysql >Connect($host);

$dbh = Mysql >Connect($host,$database);

$dbh = Mysql >Connect($host,$database,$password);

$dbh = Mysql >Connect($host,$database,$password,$user);

The connect statement needs the host name, database name, user ID, and 

password. The first four statements assume some or all connection information 

from the environment. If no 

$database

 parameter is given, a 

SelectDB

 statement 

has to be provided to connect to a database. In Example 7 16 the 

connect 

syntax to a MySQL database is shown. For simplicity reasons the error handling 

is not included in following examples.

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MySQL to DB2 UDB Conversion Guide