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我是一个新手，哎呀..类VS功能空中接力
我要通过这本书Php 5 social networking这本书给了 一步步的说明使用哎呀从头创建一个社交网站。
的第一步是在书中给出的是创建下面给出的任务一堆核心类：
数据库访问
模板管理
认证
电子邮件发送
URL处理
然后，他们使用了一个注册表类来包装这些对象。
这是数据库访问类的代码：
/**
* Database management/access class: basic abstraction
*
* @author Michael Peacock
* @version 1.0
*
*/
class Mysqldb {
/**
* Allows multiple database connections
* each connection is stored as an element in the array, and the
* active connection is maintained in a variable (see below)
*/
private $connections = array();
/**
* Tells the DB object which connection to use
* setActiveConnection($id) allows us to change this
*/
private $activeConnection = 0;
/**
* Queries which have been executed and the results cached for
* later, primarily for use within the template engine
*/
private $queryCache = array();
/**
* Data which has been prepared and then cached for later usage,
* primarily within the template engine
*/
private $dataCache = array();
/**
* Number of queries made during execution process
*/
private $queryCounter = 0;
/**
* Record of the last query
*/
private $last;
/**
* Reference to the registry object
*/
private $registry;
/**
* Construct our database object
*/
public function __construct(Registry $registry) {
$this->registry = $registry;
}
/**
* Create a new database connection
* @param String database hostname
* @param String database username
* @param String database password
* @param String database we are using
* @return int the id of the new connection
*
*/
public function newConnection($host, $user, $password, $database) {
$this->connections[] = new mysqli($host, $user, $password, $database);
$connection_id = count($this->connections) - 1;
if (mysqli_connect_errno()) {
trigger_error('Error connecting to host. ' . $this->connections[$connection_id]->error, E_USER_ERROR);
}
return $connection_id;
}
/**
* Change which database connection is actively used for the next
* operation
* @param int the new connection id
* @return void
*
*/
public function setActiveConnection(int $new) {
$this->activeConnection = $new;
}
/**
* Execute a query string
* @param String the query
* @return void
*
*/
public function executeQuery($queryStr) {
if (! $result = $this->connections[$this->activeConnection]->query($queryStr))
{
trigger_error('Error executing query: ' . $queryStr . ' -
' . $this->connections[$this->activeConnection]->error, E_USER_ERROR);
} else
{
$this->last = $result;
}
}
/**
* Get the rows from the most recently executed query, excluding
* cached queries
* @return array
*
*/
public function getRows() {
return $this->last->fetch_array(MYSQLI_ASSOC);
}
/**
* Delete records from the database
* @param String the table to remove rows from
* @param String the condition for which rows are to be removed
* @param int the number of rows to be removed
* @return void
*
*/
public function deleteRecords($table, $condition, $limit) {
$limit = ($limit == '') ? '' : ' LIMIT ' . $limit;
$delete = "DELETE FROM {$table} WHERE {$condition} {$limit}";
$this->executeQuery($delete);
}
/**
* Update records in the database
* @param String the table
* @param array of changes field => value
* @param String the condition
* @return bool
*
*/
public function updateRecords($table, $changes, $condition) {
$update = "UPDATE " . $table . " SET ";
foreach($changes as $field => $value) {
$update .= "`" . $field . "`='{$value}',";
}
// remove our trailing ,
$update = substr($update, 0, - 1);
if ($condition != '') {
$update .= "WHERE " . $condition;
}
$this->executeQuery($update);
return true;
}
/**
* Insert records into the database
* @param String the database table
* @param array data to insert field => value
* @return bool
*
*/
public function insertRecords($table, $data) {
// setup some variables for fields and values
$fields = "";
$values = "";
// populate them
foreach($data as $f => $v) {
$fields .= "`$f`,";
$values .= (is_numeric($v) && (intval($v) == $v)) ? $v . "," : "'$v',";
}
// remove our trailing ,
$fields = substr($fields, 0, - 1);
// remove our trailing ,
$values = substr($values, 0, - 1);
$insert = "INSERT INTO $table ({$fields}) VALUES({$values})";
// echo $insert;
$this->executeQuery($insert);
return true;
}
/**
* Sanitize data
* @param String the data to be sanitized
* @return String the sanitized data
*
*/
public function sanitizeData($value) {
// Stripslashes
if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
}
// Quote value
if (version_compare(phpversion(), "4.3.0") == "-1") {
$value = $this->connections[$this->activeConnection]->escape_string($value);
} else {
$value = $this->connections[$this->activeConnection]->real_escape_string($value);
}
return $value;
}
/**
* Get the rows from the most recently executed query, excluding
* cached queries
* @return array
*
*/
public function getRows() {
return $this->last->fetch_array(MYSQLI_ASSOC);
}
public function numRows() {
return $this->last->num_rows;
}
/**
* Gets the number of affected rows from the previous query
* @return int the number of affected rows
*
*/
public function affectedRows() {
return $this->last->affected_rows;
}
/**
* Deconstruct the object
* close all of the database connections
*/
public function __deconstruct() {
foreach($this->connections as $connection) {
$connection->close();
}
}
}
使用糟糕据我所知的主要目的是允许应用程序很容易进化 到不断变化的要求（来源：Design Patterns explained a new persective）和它们在本书中给出了一些很好的例子 来解释这一点。
所以我的问题是，在这种情况下，应用程序需求中可能发生什么变化需要使用数据库管理的类 ，而不是让我们说使用一堆函数来完成工作？
在数据库类驻留在DB_driver.php和DB_active_rec.php. 有什么区别将使其如果他们把这些数据库的功能在帮助文件，而不是我已经看到了同样的事情在codeigniter一个将它放在一个库？
我已经通过在这个论坛上给出的答案走了，但他们没有回答 从一个要求点这个问题
谢谢..
只是尝试使用函数来实现它并进行比较。 – zerkms