MySQL: can't "select from databasename.tablename" via custom query

[Humulus]

I'm trying to use custom queries with MySQL.
A simple working statement is:

 SELECT * FROM databasename.tablename

But when I try to make databasename a parameter:

 SELECT * FROM ?.tablename

it doesn't work, because the parameter is recognized as text and automatically padded with single quotes (') like

 SELECT * FROM 'databasename'.tablename

Is it possible to change the plugin, so it takes the parameters literally?