Sequel
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Sequel is a Ruby ORM and database toolkit that provides an ActiveRecord-like interface for working with databases. It supports SQLite, MySQL, PostgreSQL, and other databases. With Sequel, you can connect to databases, run SQL queries to retrieve and manipulate data, define models, and establish associations between models. Queries can be chained and return dataset objects. Sequel offers features like validations, hooks, migrations, and transactions for managing models and data.
![DB[:items]](https://image.slidesharecdn.com/sequel-120114000138-phpapp01/85/Sequel-20-320.jpg)
![Chainable
DB[:Items]
SELECT * FROM `items`](https://image.slidesharecdn.com/sequel-120114000138-phpapp01/85/Sequel-22-320.jpg)
![Chainable
DB[:Items] where(‘price > 10’)
SELECT * FROM `items`
WHERE (price > 100)](https://image.slidesharecdn.com/sequel-120114000138-phpapp01/85/Sequel-23-320.jpg)
![Chainable
DB[:Items] where(‘price > 10’) order(:name) limit(10)
SELECT * FROM `items`
WHERE (price > 100)
ORDER BY `name` LIMIT 10](https://image.slidesharecdn.com/sequel-120114000138-phpapp01/85/Sequel-24-320.jpg)
![Two type of returns
Dataset return Dataset’
id name
Dataset return
1 a
2 b
DB[:items].limit(10).all](https://image.slidesharecdn.com/sequel-120114000138-phpapp01/85/Sequel-25-320.jpg)
Sequel
- 1. Sequel pure Ruby DB Toolkit
- 3. Ruby Toolbox • Database Abstraction - Adapters • DSL - Ruby • ORM - Models
- 4. Adapters • SQLite • MySQL (2) • PostgreSQL • DBI
- 5. gem install sequel gem install sqlite3 gem install mysql2
- 6. Connect to DB • DB = Sequel.sqlite (in-memory)
- 7. Connect to DB • DB = Sequel.sqlite (in-memory) • DB = Sequel.connect (‘sqlite://test.db’)
- 8. Connect to DB • DB = Sequel.sqlite (in-memory) • DB = Sequel.connect (‘sqlite://test.db’) • DB = Sequel.connect (‘mysql://...’) • DB = Sequel.connect (‘postgres://...’)
- 9. Ruby Toolbox sequel -E sqlite://test.db
- 10. Database Object
- 11. DB - Database Object • DB.tables • DB.table_exists?(:items) • DB.schema(:items) • DB.add_index :items, :name
- 12. SQL QUIZ ! Rename table
- 13. SQL QUIZ ! DB.rename_table :items , :mono
- 14. SQL QUIZ ! ALTER TABLE `items` RENAME TO `mono`
- 16. DB.run(‘ALTER TABLE ’) DB.rename_table
- 17. Dataset Object
- 19. Dataset object SQL Query as Object
- 20. DB[:items]
- 21. Immutable Dataset Return Dataset (copy)
- 22. Chainable DB[:Items] SELECT * FROM `items`
- 23. Chainable DB[:Items] where(‘price > 10’) SELECT * FROM `items` WHERE (price > 100)
- 24. Chainable DB[:Items] where(‘price > 10’) order(:name) limit(10) SELECT * FROM `items` WHERE (price > 100) ORDER BY `name` LIMIT 10
- 25. Two type of returns Dataset return Dataset’ id name Dataset return 1 a 2 b DB[:items].limit(10).all
- 27. Model
- 28. require ‘sequel’ class Item < Sequel::Model Dataset end
- 29. Associations class Item < Sequel::Model many_to_one :users end class User < Sequel::Model one_to_many :items end
- 30. Associations ActiveRecord Sequel belongs_to many_to_one has_many one_to_many has_and_belongs_to... many_to_many has_one one_to_one
- 31. Other features • Model validations - validate_* • Model hooks - before, after • Migrations • Transactions
- 32. Questions?