Tip #23 – How to create a reference to an alternate key
Sometimes, you want the reference between two tables to reference an alternate key and not the primary key. Here's how you can do it in Vertabelo.
In this example, we want to model cars and their owners using
car table has an alternate key consisting of the
We want the
owner table to refer to the
car table, but using the car table’s alternate key. Let’s start with a typical reference by switching to a reference in the toolbox and putting a line from the
car table to the
Now, we have a reference using the
car table’s primary key. Our current goal is to switch it to the alternate key.
Let’s change reference properties. Delete the
car_id column pair from the reference:
Then add a new one – between the
Finally, rename the
car_id column in the
owner table to
car_vin and change its type to char(17), just like in the original
Now, our reference is using an alternate key.