Rewrite properDB.js to provide 2 functions
1) execute a command for a result (for SELECT)
2) execute a command and run success/error callback (for add, delete, etc)
Let user set myDB.log = true/false, true will print out SQL statements onto the log console.
Rewrite properDB.js to chain queries and execute only when .commit() is called or equivalent. And rollback by returning true/false in the error callback.