Open to do actions for SQL::Statement 1.xx
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Speed up join_2_tables:
  join_2_tables neither respect joins described in where_clause nor it
  left out unnecessary rows:
  SELECT * FROM ... WHERE t1.c1 = t2.c4 AND t2.c2 = 'Take me'
  Entire t1 will be cross joined t2 and than filtered.
  Proposals are welcome - even codeless, just ideas.

Open to do actions for SQL::Statement 2.xx
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Rewrite Parser to use a grammar (e.g. like SQL::Translator::Parser)
  + Implement ANSI SQL grammar as default
  + Be flexible which grammars to use (as currently supported)
* Rewrite Statement handler to have command instances per command
  + Use sub-classes for different join behaviors to reduce flag
    comparing in inner loops
* Add Optimizer for conditions (constant first, ...)
* Add Sub-Select support
