DBI 接口APIs
以下是重要的DBI例程，可以根據要求使用Perl程序操作SQLite數據庫。如果更復雜的應用程序，那么可以看看到的Perl DBI官方文檔。

S.N. API & 描述
1 DBI->connect($data_source, “userid”, “password”, %attr)
建立數據庫連接或會話，請求數據源。如果連接成功，則返回一個數據庫句柄對象。

數據源的形式如 : DBI:Pg:dbname=$database;host=127.0.0.1;port=5432 PG是PostgreSQL驅動程序名稱，testdb的數據庫的名稱。

2 $dbh?>do($sql)
常規準備并執行一個SQL語句。返回受影響的行數或者undef錯誤。-1表示返回值的行數是不知道，不適用，或不可用。這里的$dbh是DBI-> connect（）調用返回的句柄。 yiibai.com

3 $dbh?>prepare($sql)
這為以后的執行程序準備一份聲明，由數據庫引擎，并返回一個引用語句句柄對象。

4 sth是$dbh?>prepare($sql) 調用返回一個語句句柄。

5 $sth->fetchrow_array()
此例程讀取下一行的數據，并返回一個列表，其中包含的字段值。返回空字段為undef值在列表中。

6 $DBI::err這相當于$h->err，$h為任何手柄類型，如$dbh, $sth或 $drh。返回從最后一個驅動方法，稱為本地數據庫引擎錯誤代碼。

7 $DBI::errstr這相當于$h->errstr，$h是任何手柄類型像$dbh, $sth或 $drh。這將返回本地數據庫引擎的錯誤消息，從最后DBI方法調用。 www.yiibai.com

8 $dbh->disconnect()
此例程關閉先前打開的數據庫連接，通過調用DBI->connect()。

連接到數據庫
下面的Perl代碼顯示了如何連接到一個現有的數據庫。如果數據庫不存在，那么它就會被創建，終于將返回一個數據庫對象。

#!/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";

現在讓我們運行上面的程序來打開我們的數據庫testdb中，如果成功打開數據庫，然后它會給下面的消息：

Open database successfully

創建表
下面的Perl程序將在以前創建的數據庫中創建一個表：

#!/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();

上述程序執行時，它會在數據庫testdb 創建COMPANY 表公司，它會顯示以下消息：

Opened database successfully
Table created successfully
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INSERT 操作
Perl程序，顯示我們如何在上面的例子中創建COMPANY 表中的記錄： yiibai.com

#!/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();

上述程序執行時，它會創建COMPANY表中的記錄，并會顯示以下兩行：

Opened database successfully
Records created successfully
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SELECT 操作
Perl程序，表明我們如何獲取并顯示在上面的例子中創建表COMPANY 中的記錄：

#!/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();

當上述程序執行時，它會產生以下結果： yiibai.com

Opened database successfully ID = 1 NAME = Paul ADDRESS = California SALARY = 20000ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000Operation done successfully

UPDATE 操作
Perl代碼顯示如何，我們可以使用UPDATE語句來更新任何記錄，然后從COMPANY 表獲取并顯示更新的記錄：

#!/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();

當上述程序執行時，它會產生以下結果：

Opened database successfully Total number of rows updated : 1 ID = 1 NAME = Paul ADDRESS = California SALARY = 25000ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000Operation done successfully

DELETE 操作
Perl代碼顯示了我們如何使用DELETE語句刪除任何記錄，然后獲取COMPANY 表并顯示剩余記錄 :

#!/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(); yiibai.com
當上述程序執行時，它會產生以下結果：

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

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