I can globally change a field in a table by entering "update table_name set field = "new value" where field="old value". Can someone add to this command to make it possible to change globally all the links in an individual category, not in a table?

What I am trying to do is to change all the url field in a category. I don't want to change url of all the links. So far all the links are in a table called lsql_Links. Can I make changes in a category, but not in a table?