DBI 接口APIs
以下是重要的DBI例程,可以根据要求使用Perl程序操作SQLite数据库。如果更复杂的应用程序,那么可以看看到的Perl DBI官方文档。
S.N. | API & 描述 |
---|---|
1 | DBI->connect($data_source, "userid", "password", \%attr) 建立数据库连接或会话,请求数据源。如果连接成功,则返回一个数据库句柄对象。 数据源的形式如 : DBI:Pg:dbname=$database;host=127.0.0.1;port=5432 PG是PostgreSQL驱动程序名称,testdb的数据库的名称。 |
2 | $dbh->do($sql) 常规准备并执行一个SQL语句。返回受影响的行数或者undef错误。-1表示返回值的行数是不知道,不适用,或不可用。这里的$dbh是DBI-> connect()调用返回的句柄。 yiibai.com |
3 | $dbh->prepare($sql) 这为以后的执行程序准备一份声明,由数据库引擎,并返回一个引用语句句柄对象。 |
4 | $sth->execute() 此例程执行任何处理是必要的执行准备好的语句。如果发生错误,将会返回undef。一个成功的执行总是返回true。这里的$sth是$dbh->prepare($sql) 调用返回一个语句句柄。 |
5 | $sth->fetchrow_array() 此例程读取下一行的数据,并返回一个列表,其中包含的字段值。返回空字段为undef值在列表中。 |
6 | $DBI::err 这相当于$h->err,$h为任何手柄类型,如$dbh, $sth或 $drh。返回从最后一个驱动方法,称为本地数据库引擎错误代码。 |
7 | $DBI::errstr 这相当于$h->errstr,$h是任何手柄类型像$dbh, $sth或 $drh。这将返回本地数据库引擎的错误消息,从最后DBI方法调用。 www.yiibai.com |
8 | $dbh->disconnect() 此例程关闭先前打开的数据库连接,通过调用DBI->connect()。 |
连接到数据库
下面的Perl代码显示了如何连接到一个现有的数据库。如果数据库不存在,那么它就会被创建,终于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的程序来打开我们的数据库testdb中,如果成功打开数据库,然后它会给下面的消息:
Open database successfully
创建表
下面的Perl程序将在以前创建的数据库中创建一个表:
#!/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();
上述程序执行时,它会在数据库testdb 创建COMPANY 表公司,它会显示以下消息:
Opened database successfully
Table created successfully
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INSERT 操作
Perl程序,显示我们如何在上面的例子中创建COMPANY 表中的记录: yiibai.com
#!/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();
上述程序执行时,它会创建COMPANY表中的记录,并会显示以下两行:
Opened database successfully
Records created successfully
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SELECT 操作
Perl程序,表明我们如何获取并显示在上面的例子中创建表COMPANY 中的记录:
#!/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(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,它会产生以下结果: yiibai.com
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
Perl代码显示如何,我们可以使用UPDATE语句来更新任何记录,然后从COMPANY 表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();
当上述程序执行时,它会产生以下结果:
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
DELETE 操作
Perl代码显示了我们如何使用DELETE语句删除任何记录,然后获取COMPANY 表并显示剩余记录 :
#!/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(); yiibai.com
当上述程序执行时,它会产生以下结果:
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