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 /\.pm\z/ }, 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 installationi. 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 installationi. 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 postgresWelcome 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/perluse strict;use warnings;use DBI;

# db name is postgres, user is postgres and password is noneif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {print "Connected.\n";} else {print "Could not connect to DB $DBI::errstr\n";}

exit(0);

DBHandlerEx01.pl

Results:-Connected.

Danairat T.

Database Statement

172


# Connect to the databaseif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {# Statement from DB handlermy $sth = $dbh->prepare( "SELECT * FROM megaliths" )or die "Can't prepare SQL statement: $DBI::errstr\n";

# Execute the statement in the database$sth->execute()or die "Can't execute SQL statement: $DBI::errstr\n";$sth->finish()or die "Error finish the SQL statement: $DBI::errstr\n";# Disconnect database$dbh->disconnect()or warn "Error disconnecting: $DBI::errstr\n";

} else {print "Could not connect to DB $DBI::errstr\n";}

exit(0);

DBSthEx01.pl

Results:-

<no displayed result>

Danairat T.

Database Manipulation

173

• Retrieve database records

#!/usr/bin/perluse strict;use warnings;use DBI;# 1. Connect to the databaseif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {my $sth = $dbh->prepare( "SELECT * FROM megaliths" )or die "Can't prepare SQL statement: $DBI::errstr\n";

# 2. Execute the statement in the database$sth->execute() or die "Can't execute SQL statement: $DBI::errstr\n";# 3. Retrieve DB recordsmy @row;while ( @row = $sth->fetchrow_array() ) {my ($id, $name, $location, $desc, $siteId, $mapRef) = @row;print "id=$id, name=$name, location=$location, mapRef=$mapRef\n";

}# 4. Finish the statement$sth->finish() or die "Error finish the SQL statement: $DBI::errstr\n";# 5. Disconnect database$dbh->disconnect()or warn "Error disconnecting: $DBI::errstr\n";

} else {print "Could not connect to DB $DBI::errstr\n";}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


my $newRecord = "6, Stone Big, The Area 51, The most biggest stone, 3, CA 8759 993";# Connect to the databaseif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {# Prepare the statementmy $sth = $dbh->prepare( "INSERT INTO megaliths (id, name, location, description, site_type_id,mapref) VALUES (?,?,?,?,?,?)" )

or die "Can't prepare SQL statement: $DBI::errstr\n";

# Extract the input to variablemy ($id, $name, $location, $description, $site_type_id, $mapref) = split (/,/,$newRecord);

# Execute the statement in the database$sth->execute($id, $name, $location, $description, $site_type_id, $mapref)or die "Can't execute SQL statement: $DBI::errstr\n";

# Finish the statement$sth->finish() or die "Error finish the SQL statement: $DBI::errstr\n";

# Disconnect database$dbh->disconnect()or warn "Error disconnecting: $DBI::errstr\n";


DBAddEx01.pl

Results:-

<please see the db result there is one new record inserted>

Danairat T.


175

• Update records from table


my $newRecord = "6, Stone Biggest, The Area 51, The most biggest stone, 3, CA 8759 993";# Connect to the databaseif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {# Prepare the statementmy $sth = $dbh->prepare( "UPDATE megaliths SET name=? WHERE (id=?)" )or die "Can't prepare SQL statement: $DBI::errstr\n";

# Extract the input to variablemy ($id, $name, @others) = split (/,/,$newRecord);

# Execute the statement in the database$sth->execute($name, $id)or die "Can't execute SQL statement: $DBI::errstr\n";




DBUpdateEx01.pl

Results:-

<please see the db result >

Danairat T.


176

• Delete records from table


my $newRecord = "6, Stone Biggest, The Area 51, The most biggest stone, 3, CA 8759 993";# Connect to the databaseif (my $dbh = DBI->connect("dbi:Pg:dbname=postgres", "postgres", "")) {# Prepare the statementmy $sth = $dbh->prepare( "DELETE FROM megaliths WHERE (id=?)" )or die "Can't prepare SQL statement: $DBI::errstr\n";

# Extract the input to variablemy ($id, @others) = split (/,/,$newRecord);

# Execute the statement in the database$sth->execute($id)or die "Can't execute SQL statement: $DBI::errstr\n";




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

Software