week_3_day_2_afternoon.rb

- Username and password; 
- \h => help; 
-\c butterflies_app; 
-\d (desribe the table)

- cp -r butterflies_app butterflies_pg_app

-psql --help 
- psql -f butterflies.sql butterflies_app (run where the butterflies.sql is)
-\d butterflies
-We need to connect to the postgres database; 

db = PG.connect(:dbname => 'butterflies_app', :host => 'localhost')
  puts "SQL: #{sql}"
  results = db.exec(sql)
  db.close
  results
end