How can I 'Search and Replace' severity codes?

[remmesk]

We've been using Mantis out-of-the-box, with no customizations. Now my boss wants to change the severity codes to six levels 0-5 (0-Highest, 5-Lowest). Changing the display strings was easy, 'block'->0 and 'text'->5, but I'm left with the previous 'feature' and 'trivial' severity codes. So I need to do a 'search and replace' to move 'feature/trivial' -> 'text'. I believe I could use a sql "update" to modify my old bugs but I'm not much of a sql programmer (or php for that matter) and am worried that I could corrupt my database.

Could I use Mantis to perform this search and replace, kind of like 'upgrading'? Any ideas and/or code snippets would be appreciated.

Thanks for your help!!