Well, say you have all of your fonts in table 'fonts' and their names are stored in column 'name'. One way to get, say, all the fonts starting with the letter 'a' and then sort them alphabetically would be this:
SELECT * FROM fonts WHERE LOWER(SUBSTRING(name,1,1)) = 'a';
The SUBSTRING() function returns the first letter of the value in column 'name' (MySQL's SUBSTRING() works differently from PHP's substr() in that the first character has index 1 rather than 0). The LOWER() function makes it lowercase, just in case you have fonts whose names start with both uppercase and lowercase letters.