PEAR DB的使用

快递回复数据，当你不再想用fetchRow()方法来获取数据的时候，
Pear DB通过sql语句提供一些特别的方法来返回想要的数据。
这些方法有：getOne, getRow, getCol, getAssoc and getAll。
"get*() 系列方法" 可以为你做很多事情, 包括: 发起一个查询, 获取数据和清除结果。
请注意所有的Pear DB函数将可能返回一个 Pear DB_error 对象。

通过 Pear DB可以从查询结果获得更多有用的数据信息 。这些方法有:
numRows(): 通过一个"SELECT" 查询返回所有数据的数量。
numCols():通过一个"SELECT" 查询返回所有的列。
affectedRows(): 通过("INSERT", "UPDATE" or "DELETE")操作返回所有受影响的数据行数。
tableInfo():通过一个"SELECT" 查询返回一个包含数据信息的数组。

可用方法列表：
<?php
/*
* From the DB_(driver) objects
*/
// get the object with, ie:
$db = DB::connect('mysql://user:pass@localhost/my_db');
 
// Set options
$db->setErrorHandling();
$db->setFetchmode();
// Information
$db->affectedRows();
$db->tableInfo();
// Database manipulation
$db->query();
// Data fetch
$db->nextId();
$db->getOne();
$db->getRow();
$db->getCol();
$db->getAssoc();
$db->getAll();
// Place holders and execute related
$db->quote();
$db->prepare();
$db->execute();
$db->executeMultiple();
// Transactions
$db->autoCommit();
$db->commit();
$db->rollback();
// Disconnection
$db->disconnect();
 
/*
* From DB_result objects
*/
// get the object with, ie:
$res = $db->query('select * from foo');
 
// Data fetch
$res->fetchRow();
$res->fetchInto();
// Result Info
$res->numCols();
$res->numRows();
$res->tableInfo();
// Free
$res->free();
 
/*
* From DB_error objects
*/
// get the object with, ie:
$error = $db->query('select * from no_table');
 
$error->getMessage();
$error->getDebugInfo();
$error->toString();
?>

//////////////////////////////////////////////
///其他详细使用
///////////////////////////////////////////////
PEAR DB 的连接和断开

<?php
// The pear base directory must be in your include_path
require_once 'DB.php';
$user = 'foo';
$pass = 'bar';
$host = 'localhost';
$db_name = 'clients_db';

// Data Source Name: This is the universal connection string
$dsn = "mysql://$user:$pass@$host/$db_name";

// DB::connect will return a Pear DB object on success
// or a Pear DB Error object on error
// You can also set to TRUE the second param
// if you want a persistent connection:
// $db = DB::connect($dsn, true);
$db = DB::connect($dsn);

// With DB::isError you can differentiate between an error or
// a valid connection.
if (DB::isError($db)) {
         die ($db->getMessage());
}
....
// You can disconnect from the database with:
$db->disconnect();
?>
=======================

执行数据库并获得数据
<?php
// Once you have a valid DB object
...
$sql = "select * from clients";
// If the query is a "SELECT", $db->query will return
// a DB Result object on success.
// Else it simply will return a DB_OK
// On failure it will return a DB Error object.
$result = $db->query($sql);
// Always check that $result is not an error
if (DB::isError($result)) {
         die ($result->getMessage());
}

// Once you have a valid DB Result object
...
// Get each row of data on each iteration until
// there is no more rows
while ($row = $result->fetchRow()) {
     $id = $row[0];
}

?>
===============================
选择获取数据的格式
<?php
$res = $db->query('select id, name, email from users');
$row = $res->fetchRow($mode);

//With $mode = DB_FETCHMODE_ORDERED
//The default behavior is to return an ordered array.
$row = array (
     0 => <column "id" data>,
     1 => <column "name" data>,
     2 => <column "email" data>
);

$id = $row[0];

//With $mode = DB_FETCHMODE_ASSOC
//Returns an associative array with column names as array keys:
$row = array (
     'id'    => <column "id" data>,
     'name'  => <column "name" data>,
     'email' => <column "email" data>
);

$id = $row['id'];

//With $mode = DB_FETCHMODE_OBJECT
//Returns a DB_row object with column names as properties:
$row = db_row Object
(
     [id]    => <column "id" data>,
     [name]  => <column "name" data>,
     [email] => <column "email" data>
)

$id = $row->id;
?>
=============================
控制获取数据的数量
<?php
...
// the row to start fetching
$from = 50;
// how many results per page
$res_per_page = 10;
// the last row to fetch for this page
$to = $from + $res_per_page;
foreach (range($from, $to) as $rownum) {
     if (!$row = $res->fetchrow($fetchmode, $rownum)) {
         break;
     }
     $id = $row[0];
     ....
}
?>
===========================
清楚结果释放变量
<?php
...
$result = $db->query('SELECT * FROM clients');
while ($row = $result->fetchRow()) {
     ...
}
$result->free();
?>
===========================

原文地址:http://www.yaiba.net/blog/read.php/381.htm