Sequel is a simple, flexible, and powerful SQL database access toolkit for
Ruby.

Sequel provides thread safety, connection pooling and a concise DSL for
constructing SQL queries and table schemas.
Sequel includes a comprehensive ORM layer for mapping records to Ruby objects
and handling associated records.
Sequel supports advanced database features such as prepared statements, bound
variables, stored procedures, savepoints, two-phase commit, transaction
isolation, master/slave configurations, and database sharding.
Sequel currently has adapters for ADO, Amalgalite, CUBRID, DataObjects,
IBM_DB, JDBC, MySQL, Mysql2, ODBC, Oracle, PostgreSQL, SQLAnywhere, SQLite3,
Swift, and TinyTDS.