Can't get this query to work in SQL (Oracle) -

im trying return officials name, hotel manage , number of matches have refereed below database (see relational diagram below).

i have tried following, doesn't work:

select officials.name official, hotels.name hotel, -- hotel official manages count (case when officials.name = matches.referee 1 else null end) matchesrefereed officials left join hotels on  officials.staffid = hotels.manager left join matches on officials.staffid = matches.referee (case when hotels.name null '-' else hotels.name end); -- print '-' if not manage hotel 

i group function error select, , case statement @ end doesn't work.

relational diagram reference:

what dbms?

select     officials.name official,    nvl(hotels.name, '-') hotel, -- hotel official manages    count (matches.referee) matchesrefereed   officials   left join hotels on  officials.staffid = hotels.manager   left join matches on officials.staffid = matches.referee group officials.name, nvl(hotels.name, '-')