Is there a fieldtype that takes a custom SQL query for populating a select menu?

This question really is in two parts. I have a need for a completely customised select fields in two areas:

1) a single dropdown that takes a custom SQL query for populating the options.

2) a series of three dropdowns, each one dynamically populated by a custom SQL query, but needs to be controlled via the magic of jquery ajax for selecting one should change the values of the others.

I came across SP Table Select fieldtype which is great but it assumes that every row from a table will be selected. It doesn’t allow a custom query which i would need in this case due to the data structure in the table in question.

Short of attempting to create my own custom fieldtype, any bright ideas out there?