# Interface yii\db\ExpressionInterface

Implemented by | yii\db\ActiveQuery, yii\db\ArrayExpression, yii\db\Expression, yii\db\JsonExpression, yii\db\PdoValue, yii\db\Query, yii\db\conditions\ConditionInterface, yii\sphinx\ActiveQuery, yii\sphinx\Query
Available since version | 2.0.14
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/db/ExpressionInterface.php

Interface ExpressionInterface should be used to mark classes, that should be built in a special way.

The database abstraction layer of Yii framework supports objects that implement this interface and will use yii\db\ExpressionBuilderInterface to build them.

The default implementation is a class yii\db\Expression.