PostgreSQL可以使用perldbi模块与Perl集成，perldbi模块是Perl编程语言的数据库访问模块。它定义了一组提供标准数据库接口的方法、变量和约定。
下面是在您的Linux/Unix机器上安装DBI模块的简单步骤
$ 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
如果您需要为 DBI 安装 SQLite 驱动程序，那么可以按照以下方式安装它
$ wget http://search.cpan.org/CPAN/authors/id/T/TU/TURNSTEP/DBD-Pg-2.19.3.tar.gz $ tar xvfz DBD-Pg-2.19.3.tar.gz $ cd DBD-Pg-2.19.3 $ perl Makefile.PL $ make $ make install
在开始使用Perl PostgreSQL接口之前，在PostgreSQL安装目录下找到pg_hba.conf文件，添加下面一行
# IPv4 local connections: host all all 127.0.0.1/32 md5
如果postgres服务器没有运行，可以使用以下命令启动/重新启动postgres服务器-
[root@host]# service postgresql restart Stopping postgresql service: [ OK ] Starting postgresql service: [ OK ]
下面是一些重要的DBI例程，它们可以满足您在Perl程序中使用SQLite数据库的需求。如果您正在寻找更复杂的应用程序，那么您可以查看Perl DBI官方文档。
| S. No. | API & Description |
|---|---|
| 1 | DBI→connect($data_source, "userid", "password", \%attr) 建立到请求的$data_source的数据库连接或会话。如果连接成功，返回一个数据库句柄对象。 Datasource 格式为: DBI:Pg:dbname=$database;host=127.0.0.1;port=5432 Pg是PostgreSQL驱动程序名，testdb是数据库名。 |
| 2 | $dbh→do($sql) 这个例程准备并执行一个 SQL 语句。返回错误时受影响或未定义的行数。返回值-1表示行数不知道、不适用或不可用。这里 $dbh 是 DBI → connect ()调用返回的句柄。 |
| 3 | $dbh→prepare($sql) 准备一个语句供数据库引擎稍后执行，并返回对语句句柄对象的引用。 |
| 4 | $sth→execute() 执行执行准备好的语句所需的任何处理。如果发生错误，则返回undef。无论受影响的行数是多少，成功执行总是返回true。这里的$sth是一个由$dbh→prepare($sql)调用返回的语句句柄。 |
| 5 | $sth→fetchrow_array() 获取下一行数据，并将其作为包含字段值的列表返回。空字段在列表中作为undef值返回。 |
| 6 | $DBI::err 相当于$h→err，其中$h是任何句柄类型，如$dbh、$sth或$drh。这将从上次调用的驱动程序方法返回本机数据库引擎错误代码。 |
| 7 | $DBI::errstr 相当于$h→errstr，其中$h是任何句柄类型，如$dbh、$sth或$drh。这将从上次调用的DBI方法返回本机数据库引擎错误消息。 |
| 8 | $dbh->disconnect() 关闭了之前通过调用DBI→connect()打开的数据库连接。 |
下面的Perl代码展示了如何连接到现有数据库。如果数据库不存在，那么将创建它，最后将返回一个数据库对象。
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";现在，让我们运行上面给定的程序来打开数据库testdb；如果数据库成功打开，那么它将给出以下消息-
Open database successfully
下面的Perl程序将用于在先前创建的数据库中创建表
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname=$database;host=127.0.0.1;port=5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";
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 successfully\n";
}
$dbh->disconnect();当执行上面给定的程序时，它将在 testdb 中创建 COMPANY 表，并显示以下消息-
Opened database successfully Table created successfully
下面的Perl程序显示了如何在上面示例中创建的COMPANY表中创建记录-
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";
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 successfully\n";
$dbh->disconnect();当上述程序执行时，将在COMPANY表中创建给定的记录，并显示以下两行
Opened database successfully Records created successfully
下面的Perl程序显示了如何从上面示例中创建的COMPANY表中获取和显示记录-
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";
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] ."\n\n";
}
print "Operation done successfully\n";
$dbh->disconnect();当上述程序执行时，会产生如下结果
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
下面的Perl代码展示了如何使用UPDATE语句更新任何记录，然后从我们的COMPANY表中获取并显示更新后的记录：
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";
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 : $rv\n";
}
$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] ."\n\n";
}
print "Operation done successfully\n";
$dbh->disconnect();当上述程序执行时，会产生如下结果
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
下面的 Perl 代码展示了如何使用 DELETE 语句删除任何记录，然后从 COMPANY 表-中获取并显示剩余的记录
#!/usr/bin/perl
use DBI;
use strict;
my $driver = "Pg";
my $database = "testdb";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432";
my $userid = "postgres";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1 })
or die $DBI::errstr;
print "Opened database successfully\n";
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 : $rv\n";
}
$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] ."\n\n";
}
print "Operation done successfully\n";
$dbh->disconnect();当上述程序执行时，会产生如下结果
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