无涯教程-PostgreSQL - 连接Perl

标签：DBI dbh PostgreSQL database 无涯 Perl errstr print my

安装模块

可以使用Perl DBI模块将PostgreSQL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。

这是在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，则可以如下安装-

$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界面之前，请在PostgreSQL安装目录中找到 pg_hba.conf 文件，并添加以下行-

# IPv4 local connections:
host    all         all         127.0.0.1/32          md5

如果未运行postgres服务器，则可以使用以下命令启动/重新启动它:

[root@host]# service postgresql restart
Stopping postgresql service:                               [  OK  ]
Starting postgresql service:                               [  OK  ]

DBI接口API

这些参数程可以满足您在Perl程序中使用SQLite数据库的要求。如果您正在寻找更复杂的应用程序，则可以查阅Perl DBI官方文档。

S. No.	API & 描述
1	DBI→connect($data_source，" userid"，" password"，\％attr) 创建与请求的$data_source的数据库连接或会话。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，而testdb是数据库名称。
2	$dbh→do($sql) 准备并执行一个SQL语句。返回受影响或未定义错误的行数。返回值-1表示行数未知，不适用或不可用。 $dbh是DBI→connect()调用返回的句柄。
3	$dbh→prepare($sql) 准备一条语句供数据库引擎以后执行，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。无论受影响的行数如何，成功执行总是返回true。 $sth是$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。空字段作为列表中的undef值返回。
6	$DBI::err 这等效于$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	$DBI::errstr 这等效于$h→errstr，其中$h是任何句柄类型，如$dbh，$sth或$drh。这将从最后一个调用的DBI方法返回本机数据库引擎错误消息。
8	$dbh->disconnect() 关闭以前通过调用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，则将创建该数据库，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，让无涯教程运行上面给定的程序以打开数据库 testdb ；如果数据库成功打开，则将给出以下消息-

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/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();

执行上述给定程序后，它将在 testdb 中创建COMPANY表，并将显示以下消息-

Opened database successfully
Table created successfully

插入操作

以下Perl程序显示了如何在上示例中创建的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, 'Learnfk', 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 successfully
Records created successfully

选择操作

以下Perl程序说明了如何从上示例中创建的COMPANY表中获取并显示记录-

#!/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();

执行上面给定的程序时，将产生以下输出-

Opened database successfully
ID=1
NAME=Paul
ADDRESS=California
SALARY= 20000

ID=2
NAME=Learnfk
ADDRESS=Texas
SALARY= 15000

ID=3
NAME=Teddy
ADDRESS=Norway
SALARY= 20000

ID=4
NAME=Mark
ADDRESS=Rich-Mond
SALARY= 65000

Operation done successfully

更新操作

以下Perl代码显示了无涯教程如何使用UPDATE语句更新任何记录，然后从COMPANY表中获取并显示更新的记录-

#!/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();

执行上面给定的程序时，将产生以下输出-

Opened database successfully
Total number of rows updated : 1
ID=1
NAME=Paul
ADDRESS=California
SALARY= 25000

ID=2
NAME=Learnfk
ADDRESS=Texas
SALARY= 15000

ID=3
NAME=Teddy
ADDRESS=Norway
SALARY= 20000

ID=4
NAME=Mark
ADDRESS=Rich-Mond
SALARY= 65000

Operation done successfully

删除操作

以下Perl代码显示了无涯教程如何使用DELETE语句删除任何记录，然后从COMPANY表中获取并显示其余记录-

#!/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();

执行上面给定的程序时，将产生以下输出-

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

参考链接

https://www.learnfk.com/postgresql/postgresql-perl.html

标签：DBI,dbh,PostgreSQL,database,无涯,Perl,errstr,print,my
From： https://blog.51cto.com/u_14033984/8971737

无涯教程-PostgreSQL - 连接Perl

安装模块

DBI接口API

连接到数据库

创建表

插入操作

选择操作

更新操作

删除操作

参考链接

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