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 ds.score, (select count(*) from posts where owneruserid=88656 and score>=ds.score) from distinctscores ds
order by score