Dynamic Categories Size And Names?

I need to display dynamically a bunch of categories and I need the SQL algorithm to determine their size and names.

So, I have a table with one column and a variable number of records and I need to display them in GUI in pages, displaying also the page name which should be something like short name for first item to short name of last item in category.

Maximum items per page in 10 but I don't want to simply display blocks of 10 records. If the name of the 8th item starts with B and the name of the 9th item starts with C I want the first page to contain only the first 8 records. Minimum accepted items per page is 8, maximum is 10. The split should be based on the first 2 characters. Page name should be something like: first 4 chars of first item in category - first 4 chars of the last item in category.