Editing all posts at once

[benjones]

Is there a way to edit all posts at once?

To be specific I have hide tags enabled in BBCode. I'd like to place the hide tags around all file ULRLs in earlier posts. The file URLs themselves are already inside code tags. So I want to change all instances of "{code}filename{/code}" to "{hide}{code}filename{code}{/hide}"

Presumably I could use some form of Update Query on the database but I'm unfamiliar with exactly how to do it.

I tried this type of thing

"UPDATE post SET pagetext = REPLACE(pagetext, 'old name', 'new name')"

but there are a bewildering choice of of options in MyPhp 3.4.1 so I haven't managed to get this to work yet.

Sorry if this is off topic