Yii framwork crud named range NAMED SCOPE_PHP tutorial

Named range
Note: Support for named ranges starts with version 1.0.5. The original idea for named scopes came from Ruby on Rails.
A named scope represents a named query rule, which can be used in conjunction with other named scopes and applied to Active Record queries
Named scopes are mainly declared in the form of name-rule pairs in the CActiveRecord::scopes() method. The following code declares two named ranges in the Post model class,
published and recently.
class Post extends CActiveRecord
{
 …
Public function scopes()
{
         return array(
            'published'=>array(
                'condition'=>'status=1',
),
            'recently'=>array(
                'order'=>'create_time DESC',
                'limit'=>5,
),
);
}
}
Specific usage: $posts=Post::model()->published()->recently()->findAll();
Note: Named scopes can only be used with class-level methods. That is, this method must be called using ClassName::model().

Parameterized named range
Named ranges can be parameterized. For example, we want to customize the number of posts specified in the recently named scope, to achieve this, not in CActiveRecord::scopes
Instead of declaring a named range in a method, you need to define a method with the same name as the named range:
public function recently($limit=5)
{
$this->getDbCriteria()->mergeWith(array(
         'order'=>'create_time DESC',
         'limit'=>$limit,
));
Return $this;
}
Then, we can use the following statement to get the 3 most recent posts.
$posts=Post::model()->published()->recently(3)->findAll();//In the above code, the 5 most recently published posts are obtained by default.

Default scope
Model classes can have a default scope that will apply to all queries (including related ones) about this model. For example, a website that supports multiple languages ​​may only want to display
Displays content in the language specified by the current user. Because there may be many queries about the content of this website, we can define a default scope to solve this problem. For real
For this purpose, we override the CActiveRecord::defaultScope method as follows:
class Content extends CActiveRecord
{
Public function defaultScope()
{
         return array(
             'condition'=>"language='".Yii::app()->language."'",
);
}
}

Now, if the following method is called, the query rules defined above will be automatically used: $contents=Content::model()->findAll();

Practical applications
The above are several official examples. Here are the examples I use myself for your reference:

TABLE：
school:id(pk,int),name(varchar) //school
class:id(pk,int),name(varchar),s_id(fk,int) //Class
student:id(pk,int),name(varchar),s_id(int),c_id(int) //Student

Example: The query is for all classes with school "a". At this time, we can first define a relationship in the relations method in the School model to facilitate the call
public function relations()
{
Return array(
         'class'=>array(self::HAS_MANY, 'Class', 's_id'),
);
}
public function scopes()
{
Return array(
         'getAllClass'=>array(
             'with'=>'class',
),
};
}
public function getAllClass($name)
{
$this->getDbCriteria()->mergeWith(array(
         'condition'=>"t.name=$name",
));
Return $this;

}

Use: School::model()->getAllClass("a")->findAll();

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