Perl Programming - 04 Programming Database

04 - Perl Programming
Database
156
Danairat T.
Line ID: Danairat
FB: Danairat Thanabodithammachari
+668-1559-1446

Danairat T.
Perl at the client Side
Perl and Database
• Perl uses the DBI (Database Interface) for DB integration
purpose. The DBI is database-independent, which means that
it can work with vendor specific DBD (Database Driver) for any
of database, such as Postgres, mySQL, Oracle, Sybase,
Informix, Access, ODBC, etc.
157
Perl Program DBI
DBD::Pg
DBD::Oracle
Postgres
Oracle

Danairat T.
Perl and Database - Topics
• Perl Modules for Database
• Prepare Database Environment (Postgres)
• Database Handler
• Database Statement
• Database Manipulation
– Select
– Add
– Update
– Delete
158

Danairat T.
Perl Modules for Database
159
• Query your existing modules using command line:-
• perl -MFile::Find=find -MFile::Spec::Functions -lwe 'find { wanted =>
sub { print canonpath $_ if /.pmz/ }, no_chdir => 1 },
• The DBI is normally located at
/usr/perl5/vendor_perl/5.8.4/i86pc-solaris-64int/
• The DBDs are normally located at
/usr/perl5/vendor_perl/5.8.4/i86pc-solaris-64int/DBD/

Danairat T.
160
• Install the Perl DBI:-
1. Download DBI module “DBI-1.58.tar.gz” from
www.cpan.org
2. Unzip as a directory and cd to the directory
gzip -cd DBI-1.58.tar.gz | tar xf -
3. Run standard perl module installation
i. perl Makefile.PL
ii. make
iii. make test
iv. make install
4. Finished.

Danairat T.
161
• Install the Perl DBD for Postgres Database:-
1. Download DBD module “DBD-Pg-2.15.1.tar.gz” from
www.cpan.org
2. Unzip as a directory and cd to the directory
gzip -cd DBD-Pg-2.15.1.tar.gz | tar xf -
3. Run standard perl module installation
i. perl Makefile.PL
ii. make
iii. make test
iv. make install
4. Finished.

Danairat T.
Prepare Database Environment (Postgres)
162
1. Verify the system has the Postgres using pkginfo
• bash-3.00# pkginfo -i SUNWpostgr-server
• system SUNWpostgr-server The programs needed to create and run a PostgreSQL 8.1.1 7 server
• bash-3.00# pkginfo -i SUNWpostgr
• system SUNWpostgr PostgreSQL 8.1.17 client programs and libraries
• bash-3.00# pkginfo -i SUNWpostgr-libs
• system SUNWpostgr-libs The shared libraries required for any PostgreSQL 8.1.17 clients
• bash-3.00# pkginfo -i SUNWpostgr-server-data
• system SUNWpostgr-server-data The data directories needed to create and run a PostgreSQ L 8.1.8
server
• bash-3.00# pkginfo -i SUNWpostgr-contrib
• system SUNWpostgr-contrib Contributed source and binaries distributed with PostgreSQL 8.1.17
• bash-3.00# pkginfo -i SUNWpostgr-devel
• system SUNWpostgr-devel PostgreSQL 8.1.17 development header files and libraries
• bash-3.00# pkginfo -i SUNWpostgr-docs
• system SUNWpostgr-docs Extra documentation for PostgreSQL 8.1.8

Danairat T.
163
2. Create OS user for Postgres and Initialize the database:-
• #useradd -c 'PostgreSQL user' -d /export/home/postgres -m -s /bin/bash postgres
• #chown -R postgres:postgres /var/lib/pgsql
• #su - postgres
• bash-3.00$ initdb -D /var/lib/pgsql/data/mydata
• The files belonging to this database system will be owned by user "postgres".
• This user must also own the server process.
• The database cluster will be initialized with locale C.
• creating directory /var/lib/pgsql/data/mydata ... ok
• creating directory /var/lib/pgsql/data/mydata/global ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_xlog ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_xlog/archive_status ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_clog ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_subtrans ... ok

Danairat T.
164
• Create OS user for Postgres and Initialize the database (continue):-
• creating directory /var/lib/pgsql/data/mydata/pg_twophase ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_multixact/members ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_multixact/offsets ... ok
• creating directory /var/lib/pgsql/data/mydata/base ... ok
• creating directory /var/lib/pgsql/data/mydata/base/1 ... ok
• creating directory /var/lib/pgsql/data/mydata/pg_tblspc ... ok
• selecting default max_connections ... 100
• selecting default shared_buffers ... 1000
• creating configuration files ... ok
• creating template1 database in /var/lib/pgsql/data/mydata/base/1 ... ok
• initializing pg_authid ... ok
• enabling unlimited row size for system tables ... ok
• initializing dependencies ... ok
• creating system views ... ok
• loading pg_description ... ok
• creating conversions ... ok
• setting privileges on built-in objects ... ok

Danairat T.
165
• Create OS user for Postgres and Initialize the database (continue):-
• creating information schema ... ok
• vacuuming database template1 ... ok
• copying template1 to template0 ... ok
• copying template1 to postgres ... ok
• WARNING: enabling "trust" authentication for local connections
• You can change this by editing pg_hba.conf or using the -A option the
• next time you run initdb.
• Success. You can now start the database server using:
• postmaster -D /var/lib/pgsql/data/mydata
• or
• pg_ctl -D /var/lib/pgsql/data/mydata -l logfile start

Danairat T.
166
3. Start the Postgres database using:-
bash-3.00$ pg_ctl -D /var/lib/pgsql/data/mydata -l /tmp/postgres.log start
postmaster starting
bash-3.00$
4. See the Postgres Process ID
bash-3.00$ ps -ef |grep postgres
postgres 1281 1 0 12:02:58 pts/4 0:00 /usr/bin/postmaster -D /var/lib/pgsql/data/mydata
postgres 1263 1134 0 11:59:13 pts/4 0:00 -bash
postgres 1327 1263 0 12:14:46 pts/4 0:00 ps -ef

Danairat T.
167
5. Access the database:-
-bash-3.00$ psql postgres
Welcome to psql 8.1.17, the PostgreSQL interactive terminal.
Type: copyright for distribution terms
h for help with SQL commands
? for help with psql commands
g or terminate with semicolon to execute query
q to quit
postgres=#
Postgres Command Line UI Postgres Graphical UI

Danairat T.
169
6(b). Select the database:-
Postgres Graphical UI

Danairat T.
170
7. Shutdown the Postgres database:-
bash-3.00$ pg_ctl -D /var/lib/pgsql/data/mydata stop
waiting for postmaster to shut down.... done
postmaster stopped

Danairat T.
Database Handler
171
• Using the DBI to connect to Postgress and return to the DB handler
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
# db name is postgres, user is postgres and password is none
if (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {
print "Connected.n";
} else {
print "Could not connect to DB $DBI::errstrn";
}
exit(0);
DBHandlerEx01.pl
Results:-
Connected.

Danairat T.
Database Statement
172
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
# Connect to the database
# Statement from DB handler
my $sth = $dbh->prepare( "SELECT * FROM megaliths" )
or die "Can't prepare SQL statement: $DBI::errstrn";
# Execute the statement in the database
$sth->execute()
or die "Can't execute SQL statement: $DBI::errstrn";
$sth->finish()
or die "Error finish the SQL statement: $DBI::errstrn";
# Disconnect database
$dbh->disconnect()
or warn "Error disconnecting: $DBI::errstrn";
} else {
}
exit(0);
DBSthEx01.pl
Results:-
<no displayed result>

Danairat T.
Database Manipulation
173
• Retrieve database records
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
# 1. Connect to the database
my $sth = $dbh->prepare( "SELECT * FROM megaliths" )
# 2. Execute the statement in the database
$sth->execute() or die "Can't execute SQL statement: $DBI::errstrn";
# 3. Retrieve DB records
my @row;
while ( @row = $sth->fetchrow_array() ) {
my ($id, $name, $location, $desc, $siteId, $mapRef) = @row;
print "id=$id, name=$name, location=$location, mapRef=$mapRefn";
}
# 4. Finish the statement
$sth->finish() or die "Error finish the SQL statement: $DBI::errstrn";
# 5. Disconnect database
$dbh->disconnect()
} else {
}
exit(0);
DBSelectEx01.pl
Results:-
id=1, name=Stonehenge, location=Wiltshire, mapRef=SU 123 422
id=2, name=Avebury, location=Wiltshire, mapRef=SU 103 700
id=3, name=Sunhoney, location=Aberdeenshire, mapRef=NJ 716 058
id=4, name=Lundin, location=Links Fife, mapRef=NO 404 027
id=5, name=Callanish I, location=Western Isles, mapRef=NB 213 330

Danairat T.
174
• Add new records
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
my $newRecord = "6, Stone Big, The Area 51, The most biggest stone, 3, CA 8759 993";
# Prepare the statement
my $sth = $dbh->prepare( "INSERT INTO megaliths (id, name, location, description, site_type_id,
mapref) VALUES (?,?,?,?,?,?)" )
# Extract the input to variable
my ($id, $name, $location, $description, $site_type_id, $mapref) = split (/,/,$newRecord);
$sth->execute($id, $name, $location, $description, $site_type_id, $mapref)
# Finish the statement
$dbh->disconnect()
} else {
}
exit(0);
DBAddEx01.pl
Results:-
<please see the db result there is one new record inserted>

Danairat T.
175
• Update records from table
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
my $newRecord = "6, Stone Biggest, The Area 51, The most biggest stone, 3, CA 8759 993";
my $sth = $dbh->prepare( "UPDATE megaliths SET name=? WHERE (id=?)" )
my ($id, $name, @others) = split (/,/,$newRecord);
$sth->execute($name, $id)
$dbh->disconnect()
} else {
}
exit(0);
DBUpdateEx01.pl
Results:-
<please see the db result >

Danairat T.
176
• Delete records from table
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
my $newRecord = "6, Stone Biggest, The Area 51, The most biggest stone, 3, CA 8759 993";
my $sth = $dbh->prepare( "DELETE FROM megaliths WHERE (id=?)" )
my ($id, @others) = split (/,/,$newRecord);
$sth->execute($id)
$dbh->disconnect()
} else {
}
exit(0);
DBDeleteEx01.pl
Results:-
<please see the db result >

Danairat T.
Line ID: Danairat
FB: Danairat Thanabodithammachari
+668-1559-1446
Thank you

Perl Programming - 04 Programming Database

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