I have two tables,

the first is like this:

f1 | f2 | f3 | f4
-----------------
data....

the second contains info about the fields of the first:

field | info
------------
 f1      a
 f2      b
 f3      a
etc.

I would like to query the first table selecting the fields with a query on the second. So, for example, I might want to get data for fields where info is equal to "a", thus I would do "select f1, f3 from first_table". How do I do this programmatically? I was thinking about something along the lines of select (select fields from second_table where info='a') from first_table

Thanks Chris