I'm not sure there is one. What I've used in the past on SQL Server is to:
Select all within a distance threshold
Order them by distance
select rownum = 1
I'm not an expert in Oracle, but I'm in the process of migrating in to it. I'm more familiar w/ SQL Server so I don't have as much experience writing fancy queries and I still haven't learned all the functions, but something like:
select q.*, rownum from(
select t1.objectid oid1, t2.objectid oid2, sde.ST_Distance(t1.shape, t2.shape)
from table t1, table t2
where t1.objectid <> t2.objectid
order by sde.ST_Distance(t1.shape, t2.shape)
) q
where rownum =1
A lot of spatial queries seem MUCH slower in Oracle compared to SQL Server, but I have a lot to learn.
