Sequel.md

Sequel

SQL: Declarative RUBY: Object oriented

Object Relational Mappers

Written in an object oriented language and wrapped around a relational database The object classes are mapped to the data tables in the database and the object instances are mapped to individual rows in that database

Ruby ORMs

• Active Record (used a lot)
• DataMapper (used a bit)
• Sequel (pretty much not used at all)

Sequel Basics

database = Sequel.sqlite('database.sqlite3')
database.run 'CREATE TABLE people (id integer primary key autoincrement, name varchar(255))"
database.fetch "SELECT * FROM people;"
database.fetch "SELECT * from people;" do |data|
	puts data[:name]
end

Sequel abstracts SQL

database[:items].select

OR

# same as above command        
database.from(:items)      
# select the descriptions from the items table      
database.from(:items).select(:description)      
# select the id and name from the items table     
database.from(:items).select([:id, :name])     
# Using where to scope down      
database.from(:items).where(:name => 'toy')     

database.from(:people).where(:first_name => 'George').where(:phone_number => '111-111-1111')

database.from(:people).where(:id => 1).update(:last_name => "Smith")

database.from(:people).where(:id => 2).delete