我可以使用 php function 来执行相当于 mySQL 左连接的操作吗？

Question

我遇到的问题是使用下面的当前 function 加载时间太长。 正在连接的两个表各包含数千行。 保存表连接的特定 function 是下面 model 部分中的&getFields() function。

我在想我可能有一个 function 最初检查请求是编辑还是添加新的，然后处理仅在编辑查询上分离表连接（不知道如何完成此操作）。

从页面初始页面调用- 使用 html 表单和 post 方法

if(count($this->fields)){
    for($i=0;$ifields);$i++){
        $field =& $this->fields[$i];
        $se = $field->section;
        $ti = $field->title;
        $ft = $field->type;
        $na = $field->name;
        $fva = $field->field_value;
        $nu = $field->unit;
        switch($se){
            case 'header' :
                        echo 'input type="blah...

Controller 将流量定向到 Model

function __construct() {
    parent::__construct();
    $this->registerTask('add','edit');
    JRequest::setVar('view','cpanel');
}

function edit() {
    JRequest::setVar('layout','form');
    parent::display();
}

function save() {
    $model = $this->getModel('cpanel');
    $msg = $model->store();
    $link = ;
    $this->setRedirect($link, $msg);
}

拥有实际功能的Model

function __construct() {
    parent::__construct();
    global $mainframe;

    $array = JRequest::getVar('cid',  0, '', 'array');
    $this->setId((int)$array[0]);
}

function setId($id) {
    // Set id and wipe data
    $this->_id      = $id;
    $this->_data    = null;
}

function &getItem() {
    if(empty($this->_data)) {
        $query = ' SELECT * FROM #__directory_entry WHERE id = '.$this->_id;
        $this->_db->setQuery( $query );
        $this->_data = $this->_db->loadObject();
    }
    if(!$this->_data)   {
        $session =& JFactory::getSession();
        $post = $session->get('post');
        $this->_data->id = 0;
        $this->_data->title = isset($post['title'])?$post['title']:null;
    }
    return $this->_data;
}

function &getFields() {
    $query = 'select f.*, ef.field_value from #__directory_field as f left join
#__directory_enf as ef on (f.id = ef.field_id and ef.entry_id = '.$this->_id.') where
f.published = 1 order by f.ordering asc';
    $this->_db->setQuery( $query );
    $fields = $this->_db->loadObjectList();
    $session =& JFactory::getSession();
    if($session->has('post') and !$this->_id) {
        $post = $session->get('post');
        for($i=0;$ifield_value = isset($post['field_'.$fields[$i]->name])?$post['field_'.$fields[$i]->name]:null;
    }
    return $fields;
}

function store() {
    // Check for request forgeries
    JRequest::checkToken() or jexit( JText::_('Invalid Token') );
    $post = JRequest::get( 'post' );
    $session =& JFactory::getSession();
    $session->set('post', $post);

    if($post["title"] == "")
        return JText::_('Please enter the title');

    $query = 'select * from #__directory_field where published = 1';
    $this->_db->setQuery( $query );
    $fields = $this->_db->loadObjectList();
    for($i=0;$irequired and $post['field_'.$fields[$i]->name] == "")
            return JText::_($fields[$i]->title . ' is required field and can not be left blank.');
    }

    if(!$post["id"]) {
        $date =& JFactory::getDate();
        $post['create_date'] = $date->toMySQL();
        $post['ordering'] = 1;
        $query = 'select ordering from #__directory_entry order by ordering desc limit 1';
        $this->_db->setQuery( $query );
        $post['ordering'] += $this->_db->loadResult();
        $post['published'] = 1;
    }
    $me =& JFactory::getUser();
    JTable::addIncludePath(JPATH_ADMINISTRATOR.DS.'components'.DS.'com_joomd'.DS.'tables');
    $row =& JTable::getInstance('entry', 'Table');
    if (!$row->bind( $post ))
        return JText::_('Sorry some Error Occurred.');

    if (!$row->store())
        return $this->_db->getErrorMsg();

    if(!$post['id']) {
        $post['id'] = $this->_db->insertid();
        JRequest::setVar('id', $post['id']);
        $msg = JText::_('Entry successfully added!');
        $query = 'insert into #__directory_enu (entry_id, user_id) values ('.$post['id'].', '.$me->id.')';
        $this->_db->setQuery( $query );
        $this->_db->query();
    }
    else
        $msg = JText::_('Entry successfully Updated!');

    $max_size = 10000000;
    jimport('joomla.filesystem.file');
    $time = time();
    for($i=0;$itype == "image")
            $allowed = array('.jpg', '.jpeg', '.gif', '.png');
        elseif($field->type == "file")
            $allowed = array('.doc', '.docx', '.pdf', '.txt', '.exl', '.xls', '.xlsx', '.jpg', '.jpeg', '.gif', '.png', '.zip');

        $flag = true;
        $query = 'select count(*) from #__directory_enf where entry_id = ' . $post["id"] .' and field_id = ' . $field->id;
        $this->_db->setQuery( $query );
        $count = $this->_db->loadResult();
        if($field->type == "image" or $field->type == "file")   {
            $image = JRequest::getVar("field_".$field->name, null, 'FILES', 'array');
            $image_name    = str_replace(' ', '', JFile::makeSafe($image['name']));     
            $image_tmp     = $image["tmp_name"];
            if($image_name  "")   {
                $ext = strrchr($image_name, '.');
                if(!in_array($ext, $allowed))
                    return sprintf(JText::_('File type for %s is not allowed.'), $field->title);
                if(filesize($image_tmp) > $max_size)
                    return sprintf(JText::_('File size for %s exceeds the maximum file size.'), $field->title);
                if(move_uploaded_file($image_tmp, JPATH_SITE.'/files/'.$time.$image_name))
                    $post["field_".$field->name] = $time.$image_name;
                else
                    return sprintf(JText::_('Sorry File for %s could not be uploaded.'), $field->title);
            }
            else
                $flag = false;
        }
        if($flag)   {
            if($count) {
                $query = 'select id from #__directory_enf where entry_id = '.$post["id"].' and field_id = ' . $field->id;
                $this->_db->setQuery( $query );
                $field_id = $this->_db->loadResult();
                $update = new stdClass();
                $update->id = $field_id;
                $update->field_value = $post["field_".$field->name];
                $this->_db->updateObject('#__directory_enf', $update, 'id');
            }
            else {
                $insert = new stdClass();
                $insert->id = null;
                $insert->field_id = $field->id;
                $insert->entry_id = $post["id"];
                $insert->field_value = $post["field_".$field->name];
                $this->_db->insertObject('#__directory_enf', $insert, 'id');
            }
        }
    }
    $session->clear('post');
    return $msg;
}

Answer 1

Left Join 是最快的方法，但是您编写查询的方式会非常慢。

SELECT f.*, ef.field_value
   FROM #__directory_field AS f
   LEFT JOIN #__directory_enf AS ef ON (f.id = ef.field_id AND ef.entry_id = $this->_id)
   WHERE f.published = 1
   ORDER BY f.ordering ASC

您的 ON 子句是主要问题。 以这种方式编写，您是 ant 跟踪每条记录，并且没有很好地利用索引。 您将需要颠倒您的表顺序，并将 id 匹配放在 where 子句中。 像这样的东西。

SELECT ef.field_value, f.*
   FROM #__directory_enf AS ef
   LEFT JOIN #__directory_field AS f ON f.id = ef.field_id
   WHERE f.published = 1 AND ef.entry_id = $this->_id
   ORDER BY f.ordering ASC

然后，您需要确保您的数据库在 f.id 和 ef.entry_id 字段上都有索引。 这应该使您的查询速度快很多倍。