Does mandatory in MySQL Workbench mean, that referencing field cannot be NULL?

Question

I'm designing database and I'm curious about does mandatory checkbox in mysql workbench mean, that field should be null or to what does mandatory in this situation refer?

Later if necessary I will include an image of this table where this question occurred.

Tanks every on for help.

UPD:
I must say, that after I generated models SQL and looked at both tables I didn't see anything different. I'm starting to think, that this mandatory option is displayed only visually, but in functional way it doesn't mean anything.

If I'm wrong someone please help. Tanks again.

Answer 1

Ok, I found it.

Let's say you have one table called User and a second called Address and you want to make a relation between them. The example might look like this:

User
id
Name

Address
id
user_id
street

So you have a foreign key in Address for the User. If you make this relation, all fields are mandatory, so user_id is a primary key field it is not null, and Address-id is even the same, but what is Address-user_id? Is it really a part of primary key in Address? No, it doesn't help you to identify a row in this table. So the Address-user_id could be null, maybe you only got an Address or the table Address is even referenced by a table company.

The thing is, the mandatory checkbox on the "Referencing Table"-side is only for visual effects, on the opposite the checkbox on the "Referenced Table"-side makes the field nullable or not.

If mandatory, the field Address-user_id never could be null. If not mandatory, the field can be null for one row of data and no constrained will be affected.

Answer 2

I came to a conclusion that this is just a visual effect to show, that the relationship is mandatory. This option doesn't affect the generated SQL code in anyway.