SQL LIKE condition to check for integer?

Question

I am using a set of SQL LIKE conditions to go through the alphabet and list all items beginning with the appropriate letter, e.g. to get all books where the title starts wit

Answer 1

Which one of those is indexable?

This one is definitely btree-indexable:

WHERE title >= '0' AND title < ':'

Note that ':' comes after '9' in ASCII.