SQL database query wrapper
I don't do JS, even less node.js, but from the looks of it you seem to be taking in a string for your query, which means client code can do something like "select x, y, sum(z) from mytable where x = " + someValue + " group by x, y" - which is prone to SQL-injection: your client code needs to remember that.

If your executeQuery also took parameters, I think it would be clearer that when you need parameters, they should be passed as arguments to that function, not concatenated into the query string.