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In this chapter, you will learn how to use SQLite in Perl programs.
Installation
SQLite3 can be integrated with Perl using Perl DBI module, which is a database access module for the Perl programming language. It defines a set of methods, variables, and conventions that provide a standard database interface.
Following are simple steps to install DBI module on your Linux/UNIX machine −
$ wget http://search.cpan.org/CPAN/authors/id/T/TI/TIMB/DBI-1.625.tar.gz $ tar xvfz DBI-1.625.tar.gz $ cd DBI-1.625 $ perl Makefile.PL $ make $ make install
If you need to install SQLite driver for DBI, then it can be installed as follows −
$ wget http://search.cpan.org/CPAN/authors/id/M/MS/MSERGEANT/DBD-SQLite-1.11.tar.gz $ tar xvfz DBD-SQLite-1.11.tar.gz $ cd DBD-SQLite-1.11 $ perl Makefile.PL $ make $ make install
DBI Interface APIs
Following are important DBI routines, which can suffice your requirement to work with SQLite database from your Perl program. If you are looking for a more sophisticated application, then you can look into Perl DBI official documentation.
| Sr.No. | API & Description |
|---|---|
| 1 |
DBI->connect($data_source, “”, “”, %attr) Establishes a database connection, or session, to the requested $data_source. Returns a database handle object if the connection succeeds. Datasource has the form like − DBI:SQLite:dbname = ”test.db” where SQLite is SQLite driver name and test.db is the name of SQLite database file. If the filename is given as ”:memory:”, it will create an in-memory database in RAM that lasts only for the duration of the session. If the filename is actual device file name, then it attempts to open the database file by using its value. If no file by that name exists, then a new database file by that name gets created. You keep second and third parameter as blank strings and the last parameter is to pass various attributes as shown in the following example. |
| 2 |
$dbh->do($sql) This routine prepares and executes a single SQL statement. Returns the number of rows affected or undef on error. A return value of -1 means the number of rows is not known, not applicable, or not available. Here, $dbh is a handle returned by DBI->connect() call. |
| 3 |
$dbh->prepare($sql) This routine prepares a statement for later execution by the database engine and returns a reference to a statement handle object. |
| 4 |
$sth->execute() This routine performs whatever processing is necessary to execute the prepared statement. An undef is returned if an error occurs. A successful execute always returns true regardless of the number of rows affected. Here, $sth is a statement handle returned by $dbh->prepare($sql) call. |
| 5 |
$sth->fetchrow_array() This routine fetches the next row of data and returns it as a list containing the field values. Null fields are returned as undef values in the list. |
| 6 |
$DBI::err This is equivalent to $h->err, where $h is any of the handle types like $dbh, $sth, or $drh. This returns native database engine error code from the last driver method called. |
| 7 |
$DBI::errstr This is equivalent to $h->errstr, where $h is any of the handle types like $dbh, $sth, or $drh. This returns the native database engine error message from the last DBI method called. |
| 8 |
$dbh->disconnect() This routine closes a database connection previously opened by a call to DBI->connect(). |
Connect To Database
Following Perl code shows how to connect to an existing database. If the database does not exist, then it will be created and finally a database object will be returned.
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
Now, let”s run the above program to create our database test.db in the current directory. You can change your path as per your requirement. Keep the above code in sqlite.pl file and execute it as shown below. If the database is successfully created, then it will display the following message −
$ chmod +x sqlite.pl $ ./sqlite.pl Open database successfully
Create a Table
Following Perl program is used to create a table in the previously created database.
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
my $stmt = qq(CREATE TABLE COMPANY
(ID INT PRIMARY KEY NOT NULL,
NAME TEXT NOT NULL,
AGE INT NOT NULL,
ADDRESS CHAR(50),
SALARY REAL););
my $rv = $dbh->do($stmt);
if($rv < 0) {
print $DBI::errstr;
} else {
print "Table created successfullyn";
}
$dbh->disconnect();
When the above program is executed, it will create COMPANY table in your test.db and it will display the following messages −
Opened database successfully Table created successfully
NOTE − In case you see the following error in any of the operation −
DBD::SQLite::st execute failed: not an error(21) at dbdimp.c line 398
In such case, open dbdimp.c file available in DBD-SQLite installation and find out sqlite3_prepare() function and change its third argument to -1 instead of 0. Finally, install DBD::SQLite using make and do make install to resolve the problem.
INSERT Operation
Following Perl program shows how to create records in the COMPANY table created in the above example.
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
my $stmt = qq(INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (1, ''Paul'', 32, ''California'', 20000.00 ));
my $rv = $dbh->do($stmt) or die $DBI::errstr;
$stmt = qq(INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (2, ''Allen'', 25, ''Texas'', 15000.00 ));
$rv = $dbh->do($stmt) or die $DBI::errstr;
$stmt = qq(INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (3, ''Teddy'', 23, ''Norway'', 20000.00 ));
$rv = $dbh->do($stmt) or die $DBI::errstr;
$stmt = qq(INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (4, ''Mark'', 25, ''Rich-Mond '', 65000.00 ););
$rv = $dbh->do($stmt) or die $DBI::errstr;
print "Records created successfullyn";
$dbh->disconnect();
When the above program is executed, it will create the given records in the COMPANY table and it will display the following two lines −
Opened database successfully Records created successfully
SELECT Operation
Following Perl program shows how to fetch and display records from the COMPANY table created in the above example.
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
my $stmt = qq(SELECT id, name, address, salary from COMPANY;);
my $sth = $dbh->prepare( $stmt );
my $rv = $sth->execute() or die $DBI::errstr;
if($rv < 0) {
print $DBI::errstr;
}
while(my @row = $sth->fetchrow_array()) {
print "ID = ". $row[0] . "n";
print "NAME = ". $row[1] ."n";
print "ADDRESS = ". $row[2] ."n";
print "SALARY = ". $row[3] ."nn";
}
print "Operation done successfullyn";
$dbh->disconnect();
When the above program is executed, it will produce the following result.
Opened database successfully ID = 1 NAME = Paul ADDRESS = California SALARY = 20000 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000 ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000 Operation done successfully
UPDATE Operation
Following Perl code shows how to UPDATE statement to update any record and then fetch and display the updated records from the COMPANY table.
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
my $stmt = qq(UPDATE COMPANY set SALARY = 25000.00 where ID=1;);
my $rv = $dbh->do($stmt) or die $DBI::errstr;
if( $rv < 0 ) {
print $DBI::errstr;
} else {
print "Total number of rows updated : $rvn";
}
$stmt = qq(SELECT id, name, address, salary from COMPANY;);
my $sth = $dbh->prepare( $stmt );
$rv = $sth->execute() or die $DBI::errstr;
if($rv < 0) {
print $DBI::errstr;
}
while(my @row = $sth->fetchrow_array()) {
print "ID = ". $row[0] . "n";
print "NAME = ". $row[1] ."n";
print "ADDRESS = ". $row[2] ."n";
print "SALARY = ". $row[3] ."nn";
}
print "Operation done successfullyn";
$dbh->disconnect();
When the above program is executed, it will produce the following result.
Opened database successfully Total number of rows updated : 1 ID = 1 NAME = Paul ADDRESS = California SALARY = 25000 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000 ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000 Operation done successfully
DELETE Operation
Following Perl code shows how to use DELETE statement to delete any record and then fetch and display the remaining records from the COMPANY table −
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "SQLite";
my $database = "test.db";
my $dsn = "DBI:$driver:dbname=$database";
my $userid = "";
my $password = "";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfullyn";
my $stmt = qq(DELETE from COMPANY where ID = 2;);
my $rv = $dbh->do($stmt) or die $DBI::errstr;
if( $rv < 0 ) {
print $DBI::errstr;
} else {
print "Total number of rows deleted : $rvn";
}
$stmt = qq(SELECT id, name, address, salary from COMPANY;);
my $sth = $dbh->prepare( $stmt );
$rv = $sth->execute() or die $DBI::errstr;
if($rv < 0) {
print $DBI::errstr;
}
while(my @row = $sth->fetchrow_array()) {
print "ID = ". $row[0] . "n";
print "NAME = ". $row[1] ."n";
print "ADDRESS = ". $row[2] ."n";
print "SALARY = ". $row[3] ."nn";
}
print "Operation done successfullyn";
$dbh->disconnect();
When the above program is executed, it will produce the following result.
Opened database successfully Total number of rows deleted : 1 ID = 1 NAME = Paul ADDRESS = California SALARY = 25000 ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000 Operation done successfully
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