So now that we built all of our tables, it is time to actually insert some data. So here is the first thing that you're going to notice. And this very first line is really important because you'll notice that we've always done INSERT INTO table name. And then we have the values, we have the columns and the values that we're going to use. But we don't have the id field, right? So remember the id is a serial field. So we do an INSERT, we do another INSERT, and the id values are automatically generated for us. So Led Zeppelin gets number 1, AC/DC gets number 2. I mean I only said don't replicate string data. We're going to use numbers. We have now assigned, for as long as we're going to run this database, Led Zeppelin is number 1 and AC/DC is number 2. That's not really a value judgment about rock and roll, that is a primary key that's generally internal to the database. And so then we have to make these connections, right? So we want to connect the albums to the artists. Now, we have to know this and I'll show you a couple of different ways to remember these little numbers. But we basically can't tell it easily how to set these artist IDs. They're not automatically set in the same way that the IDs are automatically set. And so in this one, you notice there's no id that we're inserting and so we have a title and a artist_id and we had to remember, you just kind of write on a little piece of paper or something when you're doing it by hand and that's exactly how I do it. When I inserted on that previous screen, I remembered that Led Zeppelin was 1 and AC/DC was 2 and then I construct these by hand. And later we will see quicker ways to do this once we know a little bit more SQL. And we're going from the outside of these trees, right? So we got track, we got album, we got artist, and we got genre, right? And we're kind of working our way in from the outside to the inside and then eventually we're going to get to track. So really we're just establishing what the primary key for Rock and Metal are so that we don't have to use those over and over. So it's not too bad. Now this starts to look complex but this is part of where, if you've been having conventions all along, you just I type this really fast because it's just following a pattern, right? So we've got id, that's going to be taken care of automatically. We got the title and then we got our length, rating, and count that come in and these are in the same order. The values are in the same order as the columns. And then we have two primary keys because here on track we point to album and we point to genre. And so that's what these things are doing. So we just know which album it is and what genre it is, which album it is, what genre it is, and we just know those numbers. And when you're doing this particular following along, hopefully you're just cutting and pasting these things. But if you have to do it from scratch, you just keep track. You got a little table that is the album IDs, the artist IDs, and the genre IDs, a little piece of paper, and then you can do all this stuff, okay? So that's like a whole bunch of fuss just to not replicate these strings, right? We effectively create rows that represent those strings once and then we get primary keys for those things and then we use these primary keys in foreign key columns to make the connections. And away we go. So we've built the relationships that we need in our data. Abd it's really just numbers, it's not that much more complex. So once we've spread this data across all these tables, then we're going to actually have to reconstruct it because our graphic designer who designed this UI didn't really want numbers to be shown to the users and so we still have to reconstruct this and we want to do that efficiently and all these numbers are also a form of compression, strings are bigger than numbers and if you have millions of them, it matters. And so we're going to take this compressed data that's all now links, re-link it together, and produce the output that we want.
