 So, last week we spent a lot of time importing data into all of our different tables and then building that thing known as a relationship, making sure that my data sort of relates to other data. For example, my visit table has a connection to patient ID. Notice I have this patient ID field inside of my visit table. Well, that should directly correlate to my patient ID inside of my patient table. So one of the reasons why we want to do this is now things have become attached. We've set the foundation for my database and I can't have any problems come in. For example, that first record we have, 1527. Say for example, I wanted to delete that record. Well, I could click over here to this yellow square, right click, delete record, except notice that error I get. The record can't be deleted because invoice table has a related record. Oh, well that's actually referring to the fact that if we kind of link to this, we can actually click on that little drop down there. You can see that the invoice table, the invoice again, if we come over here, the invoice table, there it is. My ID is inside there. Again, remember, one of the things that we had selected when we were building our relationships was this idea of having referential integrity. I can't put something inside of the invoice table if it doesn't exist in the visit table. I can't bill someone for not showing up, basically. I can't bill someone for a visit they never did is the way we can think about it. So how do I tackle this? If I want to delete that visit, again, they didn't show up and we're not going to bill them, I first have to delete the linked data. I have to come in and I have to delete the invoice record first. Then now that that's removed, I can come in and delete my actual visit record.