mySQL oefeningen H8 statistische functies OPL

select count(nr), min(salaris), max(salaris), avg(salaris) count(distinct code), sum(salaris) from werknemer where afd = 'D11'
select afd, count(*) from werknemer group by afd order by afd
select afd, count(*) from werknemer group by afd order by *
select afd, count(*) from werknemer group by afd, code
select ald, geslacht, count(*) from werknemer group by afd, gesl order by afd, gesl desc
select afd from werknemer where slaris > 1000 group by afd having count(*)>=2