本文针对Yii多表联查进行汇总描述，供大家参考，具体内容如下

1、多表联查实现方法

有两种方式一种使用DAO写SQL语句实现，这种实现理解起来相对轻松，只要保证SQL语句不写错就行了。缺点也很明显，比较零散，而且不符合YII的推荐框架，最重要的缺点在于容易写错。

还有一种便是下面要说的使用YII自带的CActiveRecord实现多表联查

2、 整体框架

我们需要找到一个用户的好友关系，用户的信息放在用户表中，用户之间的关系放在关系表中，而关系的内容则放在关系类型表中。明显的我们只需要以关系表为主表联查其他两个表即可。我主要从代码的角度，分析下实现的过程。

3、CActiveRecord

我们首先需要对3张表建立相应的model，下面是关系表的代码

SocialRelation.php

<?php /** * This is the model class for table "{{social_relation}}". * * The followings are the available columns in table '{{social_relation}}': * @property integer $relation_id * @property integer $relation_type_id * @property integer $user_id * @property integer $another_user_id * * The followings are the available model relations: * @property SocialRelationType $relationType * @property AccessUser $user * @property AccessUser $anotherUser */ class SocialRelation extends CActiveRecord { /** * Returns the static model of the specified AR class. * @param string $className active record class name. * @return SocialRelation the static model class */ public static function model($className=__CLASS__) { return parent::model($className); } /** * @return string the associated database table name */ public function tableName() { return '{{social_relation}}'; } /** * @return array validation rules for model attributes. */ public function rules() { // NOTE: you should only define rules for those attributes that // will receive user inputs. return array( array('relation_type_id, user_id, another_user_id', 'numerical', 'integerOnly'=>true), // The following rule is used by search(). // Please remove those attributes that should not be searched. array('relation_id, relation_type_id, user_id, another_user_id', 'safe', 'on'=>'search'), ); } /** * @return array relational rules. */ public function relations() { // NOTE: you may need to adjust the relation name and the related // class name for the relations automatically generated below. return array( 'relationType' => array(self::BELONGS_TO, 'SocialRelationType', 'relation_type_id'), 'user' => array(self::BELONGS_TO, 'AccessUser', 'user_id'), 'anotherUser' => array(self::BELONGS_TO, 'AccessUser', 'another_user_id'), ); } /** * @return array customized attribute labels (name=>label) */ public function attributeLabels() { return array( 'relation_id' => 'Relation', 'relation_type_id' => 'Relation Type', 'relation_type_name' => 'Relation Name', 'user_id' => 'User ID', 'user_name' => 'User Name', 'another_user_id' => 'Another User', 'another_user_name' => 'Another User Name', ); } /** * Retrieves a list of models based on the current search/filter conditions. * @return CActiveDataProvider the data provider that can return the models based on the search/filter conditions. */ public function search() { // Warning: Please modify the following code to remove attributes that // should not be searched. $criteria=new CDbCriteria; $criteria->compare('relation_id',$this->relation_id); $criteria->compare('relation_type_id',$this->relation_type_id); $criteria->compare('user_id',$this->user_id); $criteria->compare('another_user_id',$this->another_user_id); $criteria->with=array( 'relationType', ); return new CActiveDataProvider($this, array( 'criteria'=>$criteria, )); } }

为了描述方便我们约定 主表为A表(执行查询的那个表)， 引用表为B表(外键所引用的表)
建议使用Gii自动生成模型，这样能够节省大量时间，为了测试方便，可以对主表生成CRUD，就是增删改查页面，其他的引用表只用生成model就行了。
1. model函数、tablename函数用于得到这个模型和得到数据库表基本信息。自动生成无需修改

2.rules函数，这个函数主要用于规定参数检验方式，注意即使有些参数不需要校验，也必须出现在rules中。不然模型将无法得到参数

3.relation函数，这个函数十分关键，用于定义表之间的关系，下面我将详细说明其中含义

'relationType' => array(self::BELONGS_TO, 'SocialRelationType', 'relation_type_id')
这句代码中结构如下
'VarName'=>array('RelationType', 'ClassName', 'ForeignKey', ...additional options)
VarName 是关系的名字，我们以后会用这个名字访问外键引用表的字段

RelationType是关系的类型，十分重要，如果设定错误会导致一些奇怪而且难以检查的错误，Yii一共提供了4种关系

BELONGS_TO（属于）: 如果表 A 和 B 之间的关系是一对多，则 表 B 属于 表 A
HAS_MANY（有多个）: 如果表 A 和 B 之间的关系是一对多，则 A 有多个 B
HAS_ONE（有一个）: 这是 HAS_MANY 的一个特例，A 最多有一个 B
MANY_MANY: 这个对应于数据库中的 多对多关系
ClassName是引用表名，就是外键所引用的表的名字，也就是B表表名

ForeignKey是外键名，主要这里填写的是外键在主表中的名字，也就是外键在A表中的表名，切记不要填错了

如果B表中是双主键可以采用下列方式实现，从软件工程的角度不推荐这样的做法，每个表最好使用独立无意义主键，不然容易出现各种问题，而且不方便管理

'categories'=>array(self::MANY_MANY, 'Category', 'tbl_post_category(post_id, category_id)'),

additional option 附加选项，很少用到
4 attributeLabels函数，这就是表属性的显示名称了，有点点像powerdesigner中code和name的关系前面一部分为数据库字段名，后面一部分为显示名称
5 search函数，用于生成表查询结果的函数，可以在此加一些限制条件，具体的使用方法就不在这里说明了，可以参考API中CDbCriteria的讲解。如果使用Gii生成那么不需要怎么修改。

同理我们生成，剩下的两个引用表

关系类型表：SocialRelationType.php

<?php /** * This is the model class for table "{{social_relation_type}}". * * The followings are the available columns in table '{{social_relation_type}}': * @property integer $relation_type_id * @property string $relation_type_name * * The followings are the available model relations: * @property SocialRelation[] $socialRelations */ class SocialRelationType extends CActiveRecord { /** * Returns the static model of the specified AR class. * @param string $className active record class name. * @return SocialRelationType the static model class */ public static function model($className=__CLASS__) { return parent::model($className); } /** * @return string the associated database table name */ public function tableName() { return '{{social_relation_type}}'; } /** * @return array validation rules for model attributes. */ public function rules() { // NOTE: you should only define rules for those attributes that // will receive user inputs. return array( array('relation_type_name', 'length', 'max'=>10), // The following rule is used by search(). // Please remove those attributes that should not be searched. array('relation_type_id, relation_type_name', 'safe', 'on'=>'search'), ); } /** * @return array relational rules. */ public function relations() { // NOTE: you may need to adjust the relation name and the related // class name for the relations automatically generated below. return array( 'socialRelations' => array(self::HAS_MANY, 'SocialRelation', 'relation_type_id'), ); } /** * @return array customized attribute labels (name=>label) */ public function attributeLabels() { return array( 'relation_type_id' => 'Relation Type', 'relation_type_name' => 'Relation Type Name', ); } /** * Retrieves a list of models based on the current search/filter conditions. * @return CActiveDataProvider the data provider that can return the models based on the search/filter conditions. */ public function search() { // Warning: Please modify the following code to remove attributes that // should not be searched. $criteria=new CDbCriteria; $criteria->compare('relation_type_id',$this->relation_type_id); $criteria->compare('relation_type_name',$this->relation_type_name,true); return new CActiveDataProvider($this, array( 'criteria'=>$criteria, )); } }

用户表：AccessUser.php

<?php /** * This is the model class for table "{{access_user}}". * * The followings are the available columns in table '{{access_user}}': * @property integer $id * @property string $name * @property string $password * @property string $lastlogin * @property string $salt * @property string $email * @property integer $status * * The followings are the available model relations: * @property SocialRelation[] $socialRelations * @property SocialRelation[] $socialRelations1 */ class AccessUser extends CActiveRecord { /** * Returns the static model of the specified AR class. * @param string $className active record class name. * @return AccessUser the static model class */ public static function model($className=__CLASS__) { return parent::model($className); } /** * @return string the associated database table name */ public function tableName() { return '{{access_user}}'; } /** * @return array validation rules for model attributes. */ public function rules() { // NOTE: you should only define rules for those attributes that // will receive user inputs. return array( array('status', 'numerical', 'integerOnly'=>true), array('name, password, salt, email', 'length', 'max'=>255), array('lastlogin', 'safe'), // The following rule is used by search(). // Please remove those attributes that should not be searched. array('id, name, password, lastlogin, salt, email, status', 'safe', 'on'=>'search'), ); } /** * @return array relational rules. */ public function relations() { // NOTE: you may need to adjust the relation name and the related // class name for the relations automatically generated below. return array( 'user_name' => array(self::HAS_MANY, 'SocialRelation', 'user_id'), 'anotherUser_name' => array(self::HAS_MANY, 'SocialRelation', 'another_user_id'), ); } /** * @return array customized attribute labels (name=>label) */ public function attributeLabels() { return array( 'id' => 'ID', 'name' => 'Name', 'password' => 'Password', 'lastlogin' => 'Lastlogin', 'salt' => 'Salt', 'email' => 'Email', 'status' => 'Status', ); } /** * Retrieves a list of models based on the current search/filter conditions. * @return CActiveDataProvider the data provider that can return the models based on the search/filter conditions. */ public function search() { // Warning: Please modify the following code to remove attributes that // should not be searched. $criteria=new CDbCriteria; $criteria->compare('id',$this->id); $criteria->compare('name',$this->name,true); $criteria->compare('password',$this->password,true); $criteria->compare('lastlogin',$this->lastlogin,true); $criteria->compare('salt',$this->salt,true); $criteria->compare('email',$this->email,true); $criteria->compare('status',$this->status); return new CActiveDataProvider($this, array( 'criteria'=>$criteria, )); } }

4、Controller
三张表介绍完了后，下面就应当介绍Controller了，同样的我们使用Gii生成主表（A表）的CRUD后就能得到controller，我们只需要对其进行一些修改即可，代码如下

SocialRelationController.php

<?php class SocialRelationController extends Controller { /** * @var string the default layout for the views. Defaults to '//layouts/column2', meaning * using two-column layout. See 'protected/views/layouts/column2.php'. */ public $layout='//layouts/column2'; /** * @return array action filters */ public function filters() { return array( 'accessControl', // perform access control for CRUD operations 'postOnly + delete', // we only allow deletion via POST request ); } /** * Specifies the access control rules. * This method is used by the 'accessControl' filter. * @return array access control rules */ public function accessRules() { return array( array('allow', // allow all users to perform 'index' and 'view' actions 'actions'=>array('index','view'), 'users'=>array('*'), ), array('allow', // allow authenticated user to perform 'create' and 'update' actions 'actions'=>array('create','update'), 'users'=>array('@'), ), array('allow', // allow admin user to perform 'admin' and 'delete' actions 'actions'=>array('admin','delete'), 'users'=>array('admin'), ), array('deny', // deny all users 'users'=>array('*'), ), ); } /** * Displays a particular model. * @param integer $id the ID of the model to be displayed */ public function actionView($id) { $this->render('view',array( 'model'=>$this->loadModel($id), )); } /** * Creates a new model. * If creation is successful, the browser will be redirected to the 'view' page. */ public function actionCreate() { $model=new SocialRelation; // Uncomment the following line if AJAX validation is needed // $this->performAjaxValidation($model); if(isset($_POST['SocialRelation'])) { $model->attributes=$_POST['SocialRelation']; if($model->save()) $this->redirect(array('view','id'=>$model->relation_id)); } $this->render('create',array( 'model'=>$model, )); } /** * Updates a particular model. * If update is successful, the browser will be redirected to the 'view' page. * @param integer $id the ID of the model to be updated */ public function actionUpdate($id) { $model=$this->loadModel($id); // Uncomment the following line if AJAX validation is needed // $this->performAjaxValidation($model); if(isset($_POST['SocialRelation'])) { $model->attributes=$_POST['SocialRelation']; if($model->save()) $this->redirect(array('view','id'=>$model->relation_id)); } $this->render('update',array( 'model'=>$model, )); } /** * Deletes a particular model. * If deletion is successful, the browser will be redirected to the 'admin' page. * @param integer $id the ID of the model to be deleted */ public function actionDelete($id) { $this->loadModel($id)->delete(); // if AJAX request (triggered by deletion via admin grid view), we should not redirect the browser if(!isset($_GET['ajax'])) $this->redirect(isset($_POST['returnUrl']) ? $_POST['returnUrl'] : array('admin')); } /** * Lists all models. */ public function actionIndex() { if(Yii::app()->user->id != null){ $dataProvider=new CActiveDataProvider( 'SocialRelation', array('criteria'=>array('condition'=>'user_id='.Yii::app()->user->id, )) ); $this->render('index',array( 'dataProvider'=>$dataProvider, )); } } /** * Manages all models. */ public function actionAdmin() { $model=new SocialRelation('search'); $model->unsetAttributes(); // clear any default values if(isset($_GET['SocialRelation'])) $model->attributes=$_GET['SocialRelation']; $this->render('admin',array( 'model'=>$model, )); } /** * Returns the data model based on the primary key given in the GET variable. * If the data model is not found, an HTTP exception will be raised. * @param integer $id the ID of the model to be loaded * @return SocialRelation the loaded model * @throws CHttpException */ public function loadModel($id) { $model=SocialRelation::model()->findByPk($id); if($model===null) throw new CHttpException(404,'The requested page does not exist.'); return $model; } /** * Performs the AJAX validation. * @param SocialRelation $model the model to be validated */ protected function performAjaxValidation($model) { if(isset($_POST['ajax']) && $_POST['ajax']==='social-relation-form') { echo CActiveForm::validate($model); Yii::app()->end(); } } }

简单介绍下其中各个函数和变量
$layout 就是布局文件的位置了，布局文件如何使用，这里不做讨论

filters 定义过滤器，这里面水很深

accessRules 访问方式，就是那些用户能够访问到这个模块

array('allow', // allow all users to perform 'index' and 'view' actions 'actions'=>array('index','view'), 'users'=>array('*'), ),

allow表示允许访问的规则如下，deny表示拒绝访问的规则如下。
action表示规定规则使用的动作

user表示规则适用的用户群组，*表示所有用户,@表示登录后的用户,admin表示管理员用户

actionXXX 各个action函数

这里值得注意的是 这个函数

public function actionIndex() { if(Yii::app()->user->id != null){ $dataProvider=new CActiveDataProvider( 'SocialRelation', array('criteria'=>array('condition'=>'user_id='.Yii::app()->user->id, )) ); $this->render('index',array( 'dataProvider'=>$dataProvider, )); } }

其中我们可以在dataProvider中设置相应的查询条件，注意这里设置是对于主表(A表)进行的，用的字段名也是主表中的，因为我们要显示的是当前用户的好友，于是，这里我们使用Yii::app()->user->id取得当前用户的id 。

loadModel 用于装载模型，这里我们可以看到findByPk查询了数据库。

performAjaxValidation 用于Ajax验证。

5、视图View

index.php

<?php $this->breadcrumbs=array( 'Social Relations', ); ?> <h1>Social Relations</h1> <?php $this->widget('zii.widgets.CListView', array( 'dataProvider'=>$dataProvider, 'itemView'=>'_view', )); ?>

我们使用一个 CListView控件进行显示，其中itemView为内容显示的具体表单，dataProvider这个是内容源，我们在controller中已经设定了。

_view.php

<?php ?> <div class="view"> <b><?php echo CHtml::encode($data->getAttributeLabel('relation_id')); ?>:</b> <?php echo CHtml::link(CHtml::encode($data->relation_id), array('view', 'id'=>$data->relation_id)); ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('relation_type_id')); ?>:</b> <?php echo CHtml::encode($data->relation_type_id); ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('relation_type_name')); ?>:</b> <?php echo $data->relationType->relation_type_name; ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('user_id')); ?>:</b> <?php echo CHtml::encode($data->user_id); ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('user_name')); ?>:</b> <?php echo $data->user->name; ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('another_user_id')); ?>:</b> <?php echo CHtml::encode($data->another_user_id); ?> <br /> <b><?php echo CHtml::encode($data->getAttributeLabel('another_user_name')); ?>:</b> <?php echo $data->anotherUser->name; ?> <br /> </div>

主要都是类似的，我们看其中的一条
复制代码 代码如下:<b><?php echo CHtml::encode($data->getAttributeLabel('relation_type_name')); ?>:</b>
<?php echo $data->relationType->relation_type_name; ?>
第一行为显示标签，在模型中我们设定的显示名就在这里体现出来
第二行为内容显示，这里的relationType是在模型中设置的关系名字，后面的relation_type_name是引用表的字段名(B表中的名字)

6、总结

通过上面的步骤，我们就实现了整个联合查询功能，效果图如下所示：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。