yii2 - Yii2 不是唯一的表/别名：'user'

Question

在“票”模型中：

public function getUser()
{
    return $this->hasOne(User::className(), ['id' => 'user_id']);
}


public function getSupervisor()
{
    return $this->hasOne(User::className(), ['id' => 'supervisor_id']);

在“票务搜索”模型中：

    $query->joinWith(['user','supervisor']);

    $query
        ->andFilterWhere(['like', 'user.surname', $this->user_id])
        ->andFilterWhere(['like', 'user.surname', $this->supervisor_id]

如果我尝试搜索主管，则会收到此错误：

Not unique table/alias: 'user'
The SQL being executed was: SELECT COUNT(*) FROM `ticket` LEFT JOIN `user` ON `ticket`.`user_id` = `user`.`id` LEFT JOIN `user` ON `ticket`.`supervisor_id` = `user`.`id` WHERE `user`.`surname` LIKE '%surname4%'

我试图更改名称用户表：

    public function getSupervisor()
    {
        return $this->hasOne(User::className(), ['id' => 'supervisor_id'])
->from(User::tableName() . 'u2');
    }

但是这个错误返回了：

You have an error in your SQL syntax; check the manual that corresponds 
to your MySQL server version for the right syntax to use near 'u2.`id` 
WHERE `supervisor`.`surname` LIKE '%surname4%'' at line 1 The SQL being executed was:
SELECT COUNT(*) FROM `ticket` LEFT JOIN `user` ON `ticket`.`user_id` = `user`.`id` LEFT JOIN `user`u2 ON
`ticket`.`supervisor_id` = `user`u2.`id` WHERE `supervisor`.`surname` LIKE '%surname4%'

Answer 1

您错过了别名之前的空格。应该：

public function getSupervisor()
{
    return $this->hasOne(User::className(), ['id' => 'supervisor_id'])
        ->from(User::tableName() . ' u2');
}

您还可以将其指定为数组键：

public function getSupervisor()
{
    return $this->hasOne(User::className(), ['id' => 'supervisor_id'])
        ->from(['u2' => User::tableName()]);
}

甚至在joinWith()这种关系中：

->joinWith([
    'supervisor' => function ($query) {
        /* @var $query \yii\db\ActiveQuery */

        $query->from(User::tableName() . ' u2');
        // or $query->from(['u2' => User::tableName()]);
    },
]);

官方文档：

• 从（）

Answer 2

从 2.0.7 版本开始有alias()方法：

public function getSupervisor()
{
    return $this->hasOne(User::className(), ['id' => 'supervisor_id'])->alias('supervisor');
}