Join Kevin Skoglund for an in-depth discussion in this video Query methods: Order, limit, and offset, part of Ruby on Rails 3 Essential Training.
We've seen how to specify the conditions of a query,…how to retrieve only the records that match a certain criteria,…but there are also three other query methods that are important to being able to…find exactly the records we want: order, limit and offset.…Order is going to specify the sort order of the written records.…Do we want them sorted alphabetically, perverse alphabetically,…sorted by ID or sorted by position? Order lets us do that.…Limit is going to limit the results that were returned.…It becomes especially important when we have a lot of records that match our conditions.…Let's say we have a database of 20,000 customers. We wouldn't want to see all…20,000 customers at once. We would probably won't see them in pages, maybe 20 at a time.…
So we would limit the results to 20. Of course if we want to view page 51 we…still only want to get 20 records back, but we also need to skip over the first…1000 records that are on the previous 50 pages.…Well offset let's us do that. Offset let's us skip over records before choosing…
- Understanding MVC (Model View Controller ) architecture
- Routing browser requests through the framework
- Responding to requests with dynamic content
- Defining associations and database relationships
- Creating, reading, updating and deleting records
- Working with forms
- Validating form data
- Reviewing built-in security features
- Authenticating users and managing user access
- Debugging and error handling
Skill Level Beginner
1. What Is Ruby on Rails?
2. Installing Ruby on Rails on a Mac
3. Installing Ruby on Rails on a Windows Machine
4. Getting Started
5. Controllers, Views, and Dynamic Content
6. Databases and Migrations
7. Models, ActiveRecord, and ActiveRelation
9. Controllers and CRUD
10. Layouts, Partials, and View Helpers
12. Data Validation
13. User Authentication
14. Improving the Simple CMS
15. Debugging and Error Handling
16. Introducing More Advanced Topics
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