I would recommended varchar(length) or text (here it's blob vs text forumblob vs text forum), but that is up to you. PHPmyadmin it's friendly, but you can modify text using the "update" statement too using console. If you are using windows I will recommend mysql administrator and if you are using mac then would be Mysql Workbench, because you have lot of tools besides to make a simple query
UPDATE: After make some search I found that you can make a text field like index but not as primary key, someone did the same question in SOF, basically the solution is to change the primary key from text to varchar, if you want to know more deeper why check this linklink