安装
PostgreSQL可以使用Perl DBI模块与Perl集成，Perl DBI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.
以下是在Linux/Unix机器上安装DBI模块的简单步骤 :
$ wget https://img01.yuandaxia.cn/Content/img/tutorials/postgresql/DBI-1.625.tar.gz $ tar xvfz DBI-1.625.tar.gz $ cd DBI-1.625 $ perl Makefile.PL $ make $ make install
如果你需要安装用于DBI的SQLite驱动程序，然后它可以安装如下 :
$ wget https://img01.yuandaxia.cn/Content/img/tutorials/postgresql/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界面之前，找到你的 pg_hba.conf 文件PostgreSQL安装目录并添加以下行 :
# IPv4 local connections:host all all 127.0.0.1/32 md5
你可以启动/重启postgres服务器，以防它运行不正常，使用以下命令 :
[root@host]# service postgresql restartStopping postgresql service: [ OK ]Starting postgresql service: [ OK ]
DBI接口API
以下是重要的DBI例程，这足以满足您的要求要求从Perl程序使用SQLite数据库.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.不. | API&描述 |
|---|---|
| 1 | DBI → connect($ data_source，"userid"，"password"，\%attr) 建立数据库连接，或会话，到请求的$ data_source.如果连接成功，则返回数据库句柄对象. 数据源的格式如下: DBI:Pg:dbname = $ database; host = 127.0.0.1; port = 5432 Pg是PostgreSQL驱动程序名称，testdb是数据库的名称. |
| 2 | $ dbh → do($ sql) 此例程准备并执行单个SQL语句.返回受影响的行数或出错时的undef.返回值-1表示行数未知，不适用或不可用.这里$ dbh是DBI → connect()调用返回的句柄. |
| 3 | $ dbh → prepare($ sql) 此例程准备一条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 → 执行() 此例程执行执行预准备语句所需的任何处理.如果发生错误，则返回undef.无论受影响的行数如何，成功执行始终返回true.这里$ sth是$ dbh → prepare($ sql)call返回的语句句柄. |
| 5 | $ sth → fetchrow_array() 此例程获取下一行数据并将其作为包含字段值的列表返回.空字段作为列表中的undef值返回. |
| 6 | $ DBI :: err 这个相当于$ h → err，其中$ h是任何句柄类型，如$ dbh，$ sth或$ drh.这将从最后一个名为的驱动程序方法返回本机数据库引擎错误代码. |
| 7 | $ DBI :: errstr 这相当于$ h → errstr，其中$ h是任何句柄类型，如$ dbh，$ sth或$ drh.这将从最后一个名为的DBI方法返回本机数据库引擎错误消息. |
| 8 | $ dbh-> disconnect() 此例程关闭先前通过调用DBI → connect()打开的数据库连接. |
连接到数据库
以下Perl代码显示了如何连接到现有数据库.如果数据库不存在，那么它将被创建，最后将返回一个数据库对象.
#!/usr/bin/perluse 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，让我们运行上面给出的程序来打开我们的数据库 testdb ;如果数据库成功打开，那么它将给出以下消息 :
Open database successfully
创建表
以下Perl程序将用于在先前创建的数据库中创建表 :
#!/usr/bin/perluse 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();当执行上述给定程序时，它将在 testdb 中创建COMPANY表，它将显示以下消息 :
Opened database successfullyTable created successfully
INSERT操作
以下Perl程序显示了我们如何在上面示例中创建的COMPANY表中创建记录 :
#!/usr/bin/perluse 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();执行上述给定程序时，它将在COMPANY表中创建给定记录，并显示以下两行 :
Opened database successfullyRecords created successfully
SELECT操作
以下Perl程序显示了我们如何从上面示例中创建的COMPANY表中获取和显示记录 :
#!/usr/bin/perluse 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();当执行上面给出的程序时，它将产生以下结果 :
Opened database successfullyID = 1NAME = PaulADDRESS = CaliforniaSALARY = 20000ID = 2NAME = AllenADDRESS = TexasSALARY = 15000ID = 3NAME = TeddyADDRESS = NorwaySALARY = 20000ID = 4NAME = MarkADDRESS = Rich-MondSALARY = 65000Operation done successfully
更新操作
以下Perl代码显示了我们如何使用UPDATE语句更新任何记录，然后从中获取和显示更新的记录我们的公司表 :
#!/usr/bin/perluse 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();当执行上面给出的程序时，它将产生以下结果 :
Opened database successfullyTotal number of rows updated : 1ID = 1NAME = PaulADDRESS = CaliforniaSALARY = 25000ID = 2NAME = AllenADDRESS = TexasSALARY = 15000ID = 3NAME = TeddyADDRESS = NorwaySALARY = 20000ID = 4NAME = MarkADDRESS = Rich-MondSALARY = 65000Operation done successfully
删除操作
以下Perl代码显示了我们如何使用DELETE语句删除任何记录，然后从我们的COMPANY表中获取并显示剩余记录 :
#!/usr/bin/perluse 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();当执行上面给出的程序时，它将产生以下结果 :
Opened database successfullyTotal number of rows deleted : 1ID = 1NAME = PaulADDRESS = CaliforniaSALARY = 25000ID = 3NAME = TeddyADDRESS = NorwaySALARY = 20000ID = 4NAME = MarkADDRESS = Rich-MondSALARY = 65000Operation done successfully