php - Yii ActiveRecord : select only first row with the same value

Question

假设我有下表:(id, subject_id)，在该表中我有以下记录:

id: 1, subject_id: 1id: 2, subject_id: 1id: 3, subject_id: 2id: 4, subject_id: 1id: 5, subject_id: 2

如何仅获取 subject_id = 1 的第一行和 subject_id = 2 的第一行:

id: 1, subject_id: 1id: 3, subject_id: 2

Answer 1

当您使用 group by 时，只会获取第一条记录。

$criteria = new CDbCriteria;
$criteria->group = 'subject_id';
$models = YouModelName::model()->findAll($criteria);