Your h-index is the highest number n, such that you have at least n questions/answers, all of which have at least n score.
Q&A about the site for people organizing, marketing or licensing open source development projects
select top(1) p.score from (select distinct z.score, z.owneruserid from posts as z) as p inner join posts as p2 on (p.owneruserid=p2.owneruserid and p.score<p2.score)
group by p.score
order by p.score desc