How do I change data type from text to bool?

I have a table/class filled with records/instances in which I accidentally
set the fields/attributes data type to text rather than boolean. I now have
75,000 records with 't' and 'f' So now I want to change the attributes to
bool? I can't find anything on changing data types in the integrated docs (I
searched them, didn't read all of them). Did I miss it? Is there an easy way
to do this? -Don

Donald Braman
donald.braman@yale.edu