Pear::DB_Table简介
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DB_Table是什么？
DB_Table 是一个访问数据库Table的OO接口，它提供了一些自动创建、插入、更新和选择的方法。自动构建往往意味着要丧失一些灵活性，DB_Table也不能例外。
安装
pear的程序库的安装没什么悬念
pear install DB_Table
DB_Table上手
官方介绍上推荐不要直接使用DB_Table Class，而是对它进行扩展，在这之上再定义字段，索引，视图等等其它自定义内容。下面来看看如何对DB_Table扩展。
基本的例子：
PHP:
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<?php
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class Guestbook extends DB_Table {
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// 稍后补充 We'll add more here later in the tutorial,
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// 注意，没有构造函数 but for now this is all we need.
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}
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?>
接着，实例化一个Guestbook
PHP:
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<?php
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// 必须的class
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require_once 'DB.php';
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require_once 'DB/Table.php';
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require_once 'Guestbook.php';
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// create a PEAR DB object
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$dsn = "phptype://username:password@localhost/database";
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$db = DB::connect($dsn);
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// set up for the Guestbook and create it, connecting
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// to a table called 'guestbook' (which does not exist
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// yet, we'll get to that in the next section)
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$book =& new Guestbook($db, 'guestbook'); // note the "=&" (very important!)
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?>
可以用PEAR_Error来查看是否有错
PHP:
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<?php
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if ($book->error) {
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// error handling code goes here; for example ...
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print_r($book->error);
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// ... although that's probably a bad idea as it will print
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// your database username and password.
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}
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?>
下面看看如何详细定义Guestbook类,这个例子里定义了guestbook表的各个字段类型：
PHP:
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<?php
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class Guestbook extends DB_Table {
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var $col = array(
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// unique row ID
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'id' => array(
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'type' => 'integer',
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'require' => true
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),
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// first name
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'fname' => array(
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'type' => 'varchar',
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'size' => 32
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),
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// last name
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'lname' => array(
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'type' => 'varchar',
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'size' => 64
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),
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// email address
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'email' => array(
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'type' => 'varchar',
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'size' => 128,
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'require' => true
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),
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// date-time signed
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'signdate' => array(
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'type' => 'date',
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'require' => true
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)
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);
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?>
如果要进一步定义guestbook表的索引，可以这样进行：
PHP:
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<?php
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class Guestbook extends DB_Table {
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// snip: var $col = array(...); 这部分内容和上面那段一样，省略
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var $idx = array(
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'id' => array(
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'type' => 'unique',
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'cols' => 'id'
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),
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'signdate' => array(
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'type' => 'normal',
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'cols' => 'signdate'
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)
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);
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}
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?>
如果索引和字段名是一样的，而且不是多字段索引，上面的定义可以简化为：
PHP:
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<?php
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var $idx = array(
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// unique index called 'id' based on the 'id' column
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'id' => 'unique',
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// normal index called 'signdate' based on the 'signdate' column
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'signdate' => 'normal'
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);
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?>
定义好表结构之后，我们看看如何进行查询，看上去非常简单，没有sql语句的痕迹：
PHP:
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<?php
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// [snip] create the $book Guestbook object
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// get the 'list' view as an array
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$rows = $book->select('list');
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print_r($rows);
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// get the 'emails' view as a DB_Result object
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$result = $book->selectResult('emails');
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print_r($result);
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?>
按条件查询：
PHP:
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<?php
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// [snip] create the $book Guestbook object
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// get 'list' view rows signed on August 14, 2003, ordered ascending by
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// last name and first name, starting at row 7 and getting 12 rows total.
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$view = 'list';
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$filter = "signdate = '2003-08-14'";
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$order = 'lname, fname';
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$start = 7;
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$count = 12;
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// as an array
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$rows = $book->select($view, $filter, $order, $start, $count);
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print_r($rows);
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// as a DB_Result object
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$rows = $book->selectResult($view, $filter, $order, $start, $count);
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print_r($result);
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?>
数据插入
PHP:
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<?php
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// [snip] create the Guestbook object ($book)
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// assign the fields and values
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$cols_vals = array(
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'id' => 1,
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'fname' => 'Thomas',
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'lname' => 'Anderson',
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'signdate' => '2003-10-12',
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'email' => 'neo@matrix.net'
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);
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// insert into the table and print results
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$result = $book->insert($cols_vals);
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print_r($result);
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?>
数据更新
PHP:
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<?php
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// [snip] create the Guestbook object ($book)
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// assign the updated fields and values
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$cols_vals = array(
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'lname' => 'Jones'
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);
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// assign the WHERE clause
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$where = "lname = 'Smith'";
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// attempt the update and print the results
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$result = $book->update($cols_vals, $where);
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print_r($result);
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?>
数据删除
PHP:
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<?php
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// [snip] create the Guestbook object ($book)
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// a where clause
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$today = date('Y-m-d'); // formatted as yyyy-mm-dd
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$where = "signdate <'$today'";
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// attempt the delete and print the results
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$result = $book->delete($where);
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print_r($result);
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?>
在上面的例子中已经没有太多sql语句的痕迹了，这可以在一定程度上简化开发过程中sql语句的编写，但是还是那句话，自动化的同时降低了灵活性，在使用DB_Table之前需要权衡。
参考
http://wiki.ciaweb.net/yawiki/index.php?area=DB_Table&page=HomePage
下载源码
http://pear.php.net/package/DB_Table
作者: Volcano 发表于August 27, 2006 at 10:43 am
Yimin 于 2006-08-27 @ 13:59:33 留言 ：
要定义字段类型也是比较麻烦的，要是直接从数据库里映射出来，那就更好了。
volcano 于 2006-08-27 @ 14:57:15 留言 ：
我觉得自动映射字段类型，应该是能够自己扩展一下的。记得以前看过类似的程序，可惜现在一时找不着了