query_bilder_sample.rb

def attributes_to_str(attrs)
  return nil unless attrs.kind_of?(Hash)

  attrs.map {|k,v| k + ' = ' + v}.join(',')
end

def build(attrs)
  <<-QUERY
  UPDATE Customers
  SET #{attributes_to_str(attrs)}
  WHERE CustomerID = 1;
  QUERY
end

set_attributes = {"ContactName" => 'Alfred Schmidt', "City" => 'Frankfurt'}

puts build(set_attributes)

# Output =>
# UPDATE Customers
# SET ContactName = Alfred Schmidt,City = Frankfurt
# WHERE CustomerID = 1;