Check If Two Tables Have The Same Column Value

I have two table on my database named Category and User. Both of them have column name ‘classification’. The value of classification for both tables came from the model I created getClassification(). Now, how can I check if the two table have the same classification? Is it possible?

Thank you guys.

    $sql = "SELECT COUNT(*) FROM category c, user u WHERE c.classification = u.classification AND = " . Yii::app()->user->id;

Ow. thank you Backslider :)