如何使用YII模型从数据库中删除数据？

在 Yii 中删除数据时，应根据场景选择合适的方法。若要删除单条记录，需先用 findOne() 或 find()->where(...)->one() 加载模型，再调用 delete() 方法，如 $model = Post::findOne(123); if ($model !== null) { $model->delete(); }；此方法会触发 beforeDelete 和 afterDelete 事件。若要删除多条记录，可使用 Post::deleteAll(['author_id' => 456]) 或带条件的 Post::deleteAll('created_at '2020-01-01'])，但该方法不会触发模型事件。对于软删除，可通过添加 is_deleted 字段并在查询中加入 ->andWhere(['is_deleted' => false]) 过滤，并通过更新字段值代替实际删除。此外，使用 deleteAll() 时务必确认条件准确性，处理关联数据时应确保外键约束，并注意事件触发差异。

In Yii, deleting data using models is straightforward, but it's important to understand the right way to do it depending on your use case. The main idea is that you can either delete a single record or multiple records, and there are different methods for each.

Deleting a Single Record

To delete a single record, you first need to load the model with the data you want to delete. This is usually done using findOne() or find()->where(...)->one(). Once you have the model instance, you can call the delete() method on it.

For example:

$model = Post::findOne(123);
if ($model !== null) {
    $model->delete();
}

This will remove the record with the primary key 123 from the Post model. Make sure to check if the model exists before calling delete() to avoid errors.

Also, keep in mind that this method triggers any beforeDelete and afterDelete events defined in your model. These are useful if you need to perform cleanup tasks or logging before or after deletion.

Deleting Multiple Records

If you want to delete more than one record at once, you can use the deleteAll() method. This method accepts conditions similar to find()->where() and deletes all matching records directly from the database.

Here’s how you might delete all posts by a specific author:

Post::deleteAll(['author_id' => 456]);

You can also pass more complex conditions:

Post::deleteAll('created_at < :date', [':date' => '2020-01-01']);

Unlike delete(), the deleteAll() method does not trigger beforeDelete or afterDelete events. So if your model relies on those for cleanup logic, they won't run here. Use this method carefully, especially when dealing with large datasets.

Soft Deletion (Optional but Common)

Sometimes you don’t want to permanently delete data but just mark it as deleted. This is called soft deletion. Yii doesn’t handle this automatically, but you can implement it easily by adding a column like is_deleted or deleted_at.

You would then filter out soft-deleted records using a query condition:

// In your model
public static function find()
{
    return parent::find()->andWhere(['is_deleted' => false]);
}

Then, instead of calling delete(), you update the flag:

$model->is_deleted = true;
$model->save(false); // skip validation if appropriate

This approach helps prevent accidental loss of data and allows recovery if needed.

A Few Things to Watch Out For

• Always double-check your conditions when using deleteAll() — a typo could wipe out more data than intended.
• If you're working with relational data, make sure related records are handled properly — Yii won't automatically manage foreign key constraints unless your database does.
• Be cautious with event triggers: delete() runs them, deleteAll() does not.

基本上就这些。

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