April 2016
Beginner to intermediate
300 pages
6h 58m
English
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Chapter 7Ecto Queries and Constraints
In the last chapter, we extended our application domain by associating videos to users. Now we’ll let users organize their videos with categories. We want our users to select which category a video belongs to upon video creation. To build this feature, you’ll need to learn more about Ecto queries and the different ways you can retrieve data from the database.
We want to build our feature safely so that corrupt data can’t creep into our database, so we’ll spend some time working with database constraints. Database engines like Postgres are called relational for a reason. A tremendous amount of time and effort has gone into tools and features that help developers define and enforce the relationships between ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.