SQLite – Perl
安裝
SQLite3 可使用 Perl DBI 模塊與 Perl 進(jìn)行集成。Perl DBI 模塊是 Perl 編程語言的數(shù)據(jù)庫訪問模塊。它定義了一組提供標(biāo)準(zhǔn)數(shù)據(jù)庫接口的方法、變量及規(guī)則。
下面顯示了在 Linux/UNIX 機器上安裝 DBI 模塊的簡單步驟：
$ 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
如果您需要為 DBI 安裝 SQLite 驅(qū)動程序，那么可按照以下步驟進(jìn)行安裝：
$ 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 接口 API
以下是重要的 DBI 程序，可以滿足您在 Perl 程序中使用 SQLite 數(shù)據(jù)庫的需求。如果您需要了解更多細(xì)節(jié)，請查看 Perl DBI 官方文檔。
| 序號 | API & 描述 |
|---|---|
| 1 | DBI->connect($data_source, "", "", \%attr) 建立一個到被請求的 $data_source 的數(shù)據(jù)庫連接或者 session。如果連接成功，則返回一個數(shù)據(jù)庫處理對象。 數(shù)據(jù)源形式如下所示：DBI:SQLite:dbname='test.db'。其中，SQLite 是 SQLite 驅(qū)動程序名稱，test.db 是 SQLite 數(shù)據(jù)庫文件的名稱。如果文件名 filename 賦值為 ':memory:'，那么它將會在 RAM 中創(chuàng)建一個內(nèi)存數(shù)據(jù)庫，這只會在 session 的有效時間內(nèi)持續(xù)。 如果文件名 filename 為實際的設(shè)備文件名稱，那么它將使用這個參數(shù)值嘗試打開數(shù)據(jù)庫文件。如果該名稱的文件不存在，那么將創(chuàng)建一個新的命名為該名稱的數(shù)據(jù)庫文件。 您可以保留第二個和第三個參數(shù)為空白字符串，最后一個參數(shù)用于傳遞各種屬性，詳見下面的實例講解。 |
| 2 | $dbh->do($sql) 該例程準(zhǔn)備并執(zhí)行一個簡單的 SQL 語句。返回受影響的行數(shù)，如果發(fā)生錯誤則返回 undef。返回值 -1 意味著行數(shù)未知，或不適用 ，或不可用。在這里，$dbh 是由 DBI->connect() 調(diào)用返回的處理。 |
| 3 | $dbh->prepare($sql) 該例程為數(shù)據(jù)庫引擎后續(xù)執(zhí)行準(zhǔn)備一個語句，并返回一個語句處理對象。 |
| 4 | $sth->execute() 該例程執(zhí)行任何執(zhí)行預(yù)準(zhǔn)備的語句需要的處理。如果發(fā)生錯誤則返回 undef。如果成功執(zhí)行，則無論受影響的行數(shù)是多少，總是返回 true。在這里，$sth 是由 $dbh->prepare($sql) 調(diào)用返回的語句處理。 |
| 5 | $sth->fetchrow_array() 該例程獲取下一行數(shù)據(jù)，并以包含各字段值的列表形式返回。在該列表中，Null 字段將作為 undef 值返回。 |
| 6 | $DBI::err 這相當(dāng)于 $h->err。其中，$h 是任何的處理類型，比如 $dbh、$sth 或 $drh。該程序返回最后調(diào)用的驅(qū)動程序（driver）方法的數(shù)據(jù)庫引擎錯誤代碼。 |
| 7 | $DBI::errstr 這相當(dāng)于 $h->errstr。其中，$h 是任何的處理類型，比如 $dbh、$sth 或 $drh。該程序返回最后調(diào)用的 DBI 方法的數(shù)據(jù)庫引擎錯誤消息。 |
| 8 | $dbh->disconnect() 該例程關(guān)閉之前調(diào)用 DBI->connect() 打開的數(shù)據(jù)庫連接。 |
連接數(shù)據(jù)庫
下面的 Perl 代碼顯示了如何連接到一個現(xiàn)有的數(shù)據(jù)庫。如果數(shù)據(jù)庫不存在，那么它就會被創(chuàng)建，最后將返回一個數(shù)據(jù)庫對象。
#!/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 successfully\n";
現(xiàn)在，讓我們來運行上面的程序，在當(dāng)前目錄中創(chuàng)建我們的數(shù)據(jù)庫 test.db。您可以根據(jù)需要改變路徑。保存上面代碼到 sqlite.pl 文件中，并按如下所示執(zhí)行。如果數(shù)據(jù)庫成功創(chuàng)建，那么會顯示下面所示的消息：
$ chmod +x sqlite.pl $ ./sqlite.pl Open database successfully
創(chuàng)建表
下面的 Perl 代碼段將用于在先前創(chuàng)建的數(shù)據(jù)庫中創(chuàng)建一個表：
#!/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 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(zhí)行時，它會在 test.db 中創(chuàng)建 COMPANY 表，并顯示下面所示的消息：
Opened database successfully Table created successfully
注意：如果您在任何操作中遇到了下面的錯誤： in case you see following error in any of the operation:
DBD::SQLite::st execute failed: not an error(21) at dbdimp.c line 398
在這種情況下，您已經(jīng)在 DBD-SQLite 安裝中打開了可用的 dbdimp.c 文件，找到 sqlite3_prepare() 函數(shù)，并把它的第三個參數(shù) 0 改為 -1。最后使用 make 和 make install 安裝 DBD::SQLite，即可解決問題。 in this case you will have 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 操作
下面的 Perl 程序顯示了如何在上面創(chuàng)建的 COMPANY 表中創(chuàng)建記錄：
#!/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 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(zhí)行時，它會在 COMPANY 表中創(chuàng)建給定記錄，并會顯示以下兩行：
Opened database successfully Records created successfully
SELECT 操作
下面的 Perl 程序顯示了如何從前面創(chuàng)建的 COMPANY 表中獲取并顯示記錄：
#!/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 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();
上述程序執(zhí)行時，它會產(chǎn)生以下結(jié)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
UPDATE 操作
下面的 Perl 代碼顯示了如何使用 UPDATE 語句來更新任何記錄，然后從 COMPANY 表中獲取并顯示更新的記錄：
#!/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 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();
上述程序執(zhí)行時，它會產(chǎn)生以下結(jié)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
DELETE 操作
下面的 Perl 代碼顯示了如何使用 DELETE 語句刪除任何記錄，然后從 COMPANY 表中獲取并顯示剩余的記錄：
#!/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 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();
上述程序執(zhí)行時，它會產(chǎn)生以下結(jié)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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