Update links in multiple posts?

Basically I have a bunch of posts with links inside them, and I need to change a part of the links.

It shows up as text underlined in blue, then once clicked it goes to a clickbank affiliate product. What I need to do is change about 200 links, changing my clickbank ID to another on the links.

Right now they’re like this: [olduser.clickbank.hop] and I need them to change to [newuser.clickbank.hop]

Is there any way to do this automatically? Such as having the mysqldatabase change “olduser” to “newuser” on all links inside the posts?

Thanks in advance.