Selecting the one before, and the one after. how?

[httpwebwitch]

I'm struggling with another tough one. Can you help?

I have a table, eg.

id ¦ name ¦ description ¦ sku ¦ categoryid
------------------------------------------
1 ¦ item1 ¦ desc1 ¦ 1111 ¦ 1
2 ¦ item2 ¦ desc2 ¦ 2222 ¦ 1
3 ¦ item3 ¦ desc3 ¦ 3333 ¦ 2
4 ¦ item4 ¦ desc4 ¦ 4444 ¦ 1
5 ¦ item5 ¦ desc5 ¦ 5555 ¦ 1
6 ¦ item6 ¦ desc6 ¦ 6666 ¦ 1

say my "current" item is #4, which is in category 1.

What I want to select from the database is - from items from the same category - the one previous to 4, and the one after 4, as ordered by their id.

That means the result I would like is:
2 ¦ item2 ¦ desc2 ¦ 2222 ¦ 1
5 ¦ item5 ¦ desc5 ¦ 5555 ¦ 1

Note that item #3 is not in the same category, so it is not returned. #2 is.

Mind that the id may not be sequential, so I can't fudge it with (id - 1) or (id + 1)

How can I do this?

[httpwebwitch]

hm. never mind, I'll just do it with 2 queries

select * FROM tablename WHERE categoryid = 1 AND itemid < 4 order by itemid desc limit 1
select * FROM tablename WHERE categoryid = 1 AND itemid > 4 order by itemid limit 1

[coopster]

(SELECT * FROM tablename WHERE categoryid = 1 AND itemid < 4 ORDER BY itemid DESC LIMIT 1) 
UNION 
(SELECT * FROM tablename WHERE categoryid = 1 AND itemid > 4 ORDER BY itemid LIMIT 1)