Inserting multiple rows at once into SQLite3 using raw SQL

sqlinsert.rb

# values_to_insert is an array of type 
# [ 
#   [val1.1, val1.2]
#   [val2.1, val2.2],
#   [val3.1, val3.2],
#   ...etc
# ]

sql = ActiveRecord::Base.connection

# breaking up into chunks of 499.
require 'enumerator'
values_to_insert.each_slice(499) do |chunk|
  sqlcommand = "INSERT INTO tablename (value1, value2) SELECT #{chunk[0][0]} AS value1, #{chunk[0][1]} AS value2"
  chunk[1..-1].each do |value_pair|
     sqlcommand += " UNION SELECT '#{value_pair[0]}','#{value_pair[1]}'"
  end
  sql.execute(sqlcommand)
end