I used a query a few weeks ago in MySQL that described a table and suggested possible improvements to its structure. For example, if I have an int field but only the numbers 1-3 in that field, it will suggest set(1,2,3) as the type.
I think I was using phpMyAdmin but I've been through all the functions I can find - Analyze, Describe, Explain, Optimize, etc - to no avail. I can't for the life of me remember what the query was!
This is what phpMyAdmin gives me:
SELECT * FROM `table_name` PROCEDURE ANALYSE ( )