Version 4 branch should not use regex

[mattbucci]

Investigate the same approach as the WordPress SQLite implemention
https://github.com/phpmyadmin/sql-parser

https://wordpress.org/plugins/sqlite-database-integration/

Simplified structure regardless can look something like:

WPDB ->
monkey patched mySQL functions
-> parser / regex/ variable extraction
-> parsed MySQL representation (class or struct)
-> convert to Postgres representation
-> toSQL() method
-> execute against postgres database
<-- post process postgres output
<-- return data to WPDB