Type of relations 1:1

Question

'Cause when I was gonna remake the relationships in my table 1:1 1:1 -------- 1.1____ (With the dash in the middle but the straight line)

What’s the difference between us?

Answer 1

The difference in dashes has to do with the use of primary keys from one table to another. In case you use --- you will retrieve the primary key from the table with which you are making the relation, and it will remain the secondary key. In the case of ___, imports primary key from one table to the other, but now staying as primary key and not as secondary.

I think the following picture illustrates well what I mean: