Sequel: The Database Toolkit for Ruby

• Thread safety, connection pooling and a concise DSL for constructing SQL queries and table schemas.
• Comprehensive ORM layer for mapping records to Ruby objects and handling associated records.
• Advanced database features such as prepared statements, bound variables, stored procedures, savepoints, two-phase commit, transaction isolation, primary/replica configurations, and database sharding.
• With adapters for ADO, Amalgalite, IBM_DB, JDBC, MySQL, Mysql2, ODBC, Oracle, PostgreSQL, SQLAnywhere, SQLite3, TinyTDS, and Trilogy.

require "sequel"

# connect to an in-memory database
DB = Sequel.sqlite

# create an items table
DB.create_table :items do
  primary_key :id
  String :name, unique: true, null: false
  Float :price, null: false
end

# create a dataset from the items table
items = DB[:items]

# populate the table
items.insert(name: 'abc', price: rand * 100)
items.insert(name: 'def', price: rand * 100)
items.insert(name: 'ghi', price: rand * 100)

# print out the number of records
puts "Item count: #{items.count}"

# print out the average price
puts "The average price is: #{items.avg(:price)}"