Pear DB 入门指南

<?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();
 ?>

<?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());
 }
 ....
 ?>

<?php
 // 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];
 }
 ?>

<?php
 ...
 while ($result->fetchInto($row)) {
     $id = $row[0];
 }
 ?>

<?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;
 ?>

<?php
 ...
 // 1) Set the mode per call:
 while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC)) {
     [..]
 }
 while ($result->fetchInto($row, DB_FETCHMODE_ASSOC)) {
     [..]
 }
 
 // 2) Set the mode for all calls:
 $db = DB::connect($dsn);
 // this will set a default fetchmode for this Pear DB instance
 // (for all queries)
 $db->setFetchMode(DB_FETCHMODE_ASSOC);
 $result = $db->query(...);
 while ($row = $result->fetchRow()) {
     $id = $row['id'];
 }
 ?>

<?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];
     ....
 }
 ?>