many to many?

[MartinJohannessen]

This is a great tool for learning data modelling, thanks!

BUT why is there no many to many relationship? And what is a zero to one relationship?

[dineug]

This tool is a physical database modeling tool.
N:M relationships are modeled as follows.

The relationship names like "zero one" refer to the states of the PK and the FK it's pointing to, not the PK state itself.

Exceptionally, the tool accommodates the Crow's foot notation for relationships.

If the relationship notation were purely physical, only the following notation would exist.

[MartinJohannessen]

Thanks so much! This tool forced me to figure out good practices.