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Overview
Sequel is a lightweight database access toolkit for Ruby. Sequel provides thread safety, connection pooling and a concise DSL for constructing database queries and table schemas. Sequel also includes a lightweight but comprehensive ORM layer for mapping records to Ruby objects using the ActiveRecord pattern.
Sequel makes it easy to deal with multiple records without having to break your teeth on SQL.
Sequel currently has adapters for ADO, DB2, DBI, Informix, JDBC, MySQL, ODBC, OpenBase, Oracle, PostgreSQL and SQLite3.
Installing Sequel
Installing Sequel is easy:
gem install sequel
Be aware, though, that Sequel depends on database adapters for its work. For example, in order to work with sqlite3 database, you need to install the sqlite3 gem.
A Short Example
require 'rubygems'
require 'sequel'
DB = Sequel.sqlite # memory database
DB.create_table :items do # Create a new table
column :name, :text
column :price, :float
end
items = DB[:items] # Create a dataset
# Populate the table
items << {:name => 'abc', :price => rand * 100}
items << {:name => 'def', :price => rand * 100}
items << {:name => 'ghi', :price => rand * 100}
# Print out the number of records
puts "Item count: #{items.count}"
# Print out the records in descending order by price
items.reverse_order(:price).print
# Print out the average price
puts "The average price is: #{items.avg(:price)}"