RAA - safequery/3.2005.8.28

# == Changes
# Version 3 comes with real parser and improved syntax. But, unfortunately, is incompatible with versions < 3.*
#
# == Description
# Build sql query from a query template and a data hash.
# You don't have to escape values by hand or iterate over arrays
# to produce dynamic lists anymore. No sql injections. Simple and powerful ;-)
#
# == Usage
#
# 1. Create a template query.
#       safequery = 'UPDATE TABLE #:tblname# (# keys of :mydata except nil values #) VALUES (# values of :mydata except nil #)'
#
# 2. Create a source data hash.
#       hsh = {
#               :tblname => 'my_foo_table',
#               :mydata => {
#                       :a => 'AAA',
#                       :b => '',
#                       :c => nil,
#                       :d => 'DDD',
#                       :e => false
#               }
#       }
#
# 3. Get result (FooDB is used because of the 'escape' method. You can specify another name of the method as the second parameter).
#
#       sq = SafeQuery3.new( FooDB.new )
#       p sq.get( safequery, hsh )
#
# 4. The result is:
#
#    "UPDATE TABLE my_foo_table (d, e, a, b) VALUES ('DDD', false, 'AAA', '')"
#