Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Databases Querying Relational Databases Table Relationships One to One Relationships

Is ID in the Customer_Extension table both primary & foreign key?

Is ID in the Customer_Extension table both primary & foreign key?

2 Answers

Steven Parker
Steven Parker
228,978 Points

This was explained at about 1:46 in the video:

...we give it the same primary key as the original customer table.
This field, ID, is also the foreign key back to the customer table.

Kevin Gates
Kevin Gates
15,052 Points

In short, "Yes", it is both. But Steven Parker goes into more detail for how it works.