找一个查询

根据 id 查找单个记录。

$model = User::findOne($id);

根据 id 选择单列。

$model = User::findOne($id)->name;

根据条件从数据库中检索单个记录。

$model = User::find()->one();  // give first record

$model = User::find()->where(['id' => 2])->one(); // give single record based on id

根据条件从数据库中选择单列记录。

$model = User::find()->select('name,email_id')->where(['id' => 1])->one();

要么

$model = User::find()->select(['id','name','email_id'])->where(['id' => 1])->one();

排序依据

$model = User::find()->select(['id','name','email_id'])->orderBy(['id' => SORT_DESC])->one();

OR 

$model = User::find()->select(['id','name','email_id'])->orderBy(['id' => SORT_ASC])->one();