best match question: please help

Hi all,

It may be a silly question but I can not figure out how to solve my problem, here it is:

table snmpOids
---------------------------------------------------------------------------------
id | objectId | objectDescr
---------------------------------------------------------------------------------
1 | 1.3.6 | name1
2 | 1.3.6.1 | name2
3 | 1.3.6.1.2 | name3
4 | 1.3.6.1.2.1 | name4
5 | 1.0.2.3.1 | name5
6 | 1.1.2.3.1 | name6

type is VARCHAR for all the columns of snmpOids.

Let's say that I have an objectId equal to 1.3.6.1.2.1.1.1 and I want to get back from my query the best match on the objectId, which is 1.3.6.1.2.1 (closest objectId to 1.3.6.1.2.1.1.1 ). How can I do that with the less querues as possible ?
I was thinking of using the strpos() function like this

select max(length(objectId)) from snmpOids where strpos('1.3.6.1.2.1.1.1',objectid) > 1;

it gives me :
11 which correponds to the length of 1.3.6.1.2.1, the best match.

Now my problem is that I don't know how to get the objectId column. If I use

select objectId,max(length(objectId)) from snmpOids where strpos('1.3.6.1.2.1.1.1',objectid) > 1 order by objectId;
it gives me :

1.3.6 | 5
1.3.6.1 | 7
1.3.6.1.2 | 9
1.3.6.1.2.1 | 11


I just want the best match, not all the matches. I want a result like this:
1.3.6.1.2.1 | 11

PLEASE HOW CAN I GET THIS OUTPUT ????
please reply also to aimeur(at)prodigy(dot)net (my e-mail) because I've just subscribe to psql-novice mailing list I don't have the confirmation yet.

thanks,