How to write NULL to database?

Question

MySQL

There is a property (field) that has a value, for example, "bla bla bla", under certain conditions, NULL should be written to the database, DEFAULT NULL is set for this field in the database.
when I do , then emptiness or an empty string is written to the database (2 - in the picture), but definitely not NULL :D, but I need exactly NULL (1 - in the picture) UPD1: this is Yii 2, the ActiveRecord model $model->id_no = null;

Answer 1

Good evening.
You can try to solve with validation
['id_no', 'default', 'value' => null]