### TODO
- date functions - now, add_date...
- string functions rtrim, ltrim, rpad, lpad
- add pipe | concatenation
- support for order by, offset, limit (allow column name in order by, validate)
- command line interface
- support for uniqueue indexes (primary key)
- support for btree indexes
- add count min and max functions, eg aggregate functions
- support for parenthesis
- class members should have prefix m_
- add const wherever should be
- PERF in Row::Row(const Row &other), could be more efficient (memory and cpu)