sql inner join over multiple tables - sql

Question

I've given this relational scheme and following task:
Inner Join: Return a list of professors, which gives
'lehrveranstaltung' of the 'fachbereich' with the name 'informatik'.
* print 'vorname', 'ho_name', 'lv_name'
* output should sort surnames in ascending order and if they're the same in descending order
* identical lines should online shown once
now I came up with following query:
select distinct
v.vorname,
h.ho_name,
l.lv_name
--print wanted, only once
from
vorname v,
hochschulangehoeriger h,
lehrveranstaltung l
-- from these tables
inner join fachbereich f on f.fb_name = 'Informatik'
-- only the 'informatik' events
inner join prof_haelt_lv on l.lv_nr = pl.lv_nr
-- make sure 'lehrveranstaltung' is from a professor
inner join mitarbeiter mit on pl.pers_Nr = mit.pers_Nr
-- make sure dude is a prof
where
mit.ho_nr = h.ho_nr
and
mit.ho_nr = v.ho_nr -- give only names from prof
order by
2 asc,
3 desc; -- order rules
I think this works for me (can't test it properly). But when I look at it I'll wish that I came up for a bether solution since this looks kinda ugly and wrong for me.
Is there a bether way of doing this? (Have to use inner join)

Answer 1

Based on the table you have, you may use the following SQL statement
SELECT DISTINCT v.vorname,
h.ho_name,
l.lv_name
FROM vorname v
INNER JOIN hochschulangehoeriger h
ON v.ho_nr = h.ho_nr
INNER JOIN mitarbeiter m
ON m.ho_nr = h.ho_nr
INNER JOIN fachbereich f
ON f.fb_nr = m.fb_nr
AND f.fb_name = 'Informatik'
INNER JOIN lehrveranstaltung l
ON l.fb_nr = f.nb_nr
INNER JOIN professor p
ON p.pers_nr = m.pers_nr
INNER JOIN prof_haelt_lv pl
ON pl.pers_nr = p.pers_nr
AND pl.lv_nr = l.lv_nr
ORDER BY 2,
3 DESC;
Also, these section on your SQL, this has no connection to any table in your SQL
inner join fachbereich f on f.fb_name = 'Informatik'
-- only the 'informatik' events
you forgot the alias for prof_haelt_lv
inner join prof_haelt_lv on l.lv_nr = pl.lv_nr
-- make sure 'lehrveranstaltung' is from a professor