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.
Preguntas y respuestas para programadores y profesionales de la informática
with distinctscores as
select distinct score from posts where owneruserid=88656
select top(1) score from (select ds.score, postcount=(select count(*) from posts where owneruserid=88656 and score>=ds.score) from distinctscores ds)scorecomp where postcount>=score
order by score desc