You can probably go about the perl side in a much cleaner fashion (someone else will likely speak to that), but on the SQL side you can change the COLLATION to perform case-sensitive searches.

Either change the COLLATION on the table or do it per-query:

   SELECT `id`, `rec` FROM `memrecs` WHERE `rec` COLLATE latin1_bin LIKE ?;

then bind the like expression as normal.

You might also try latin_cs.

-David

FYI, I found that info in about 15 seconds on Google with the query +mysql +like +where +"case sensitive".