Relational algebra , tried everything, just don't know how to do this -

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the following relational tables/schemes given:

in bold primary key, in italics foreign key:

-city(name,country,population)

-venue(vid,capacity,name)

-concert(kid,id,did,duration)

-performer(id,kid,age,name)

-ticket(tid,kid,price,type)

now assignment find concerts there more vip tickets other tickets. vip of attribute type, in tickets. have thought problem while. main idea group kid,type,count(*) in (tickets) , somehow add tickets of type != vip , select less vip tickets, don;t know how formally..

something work:

  select concert.name concert        inner join ticket on concert.kid = ticket.kid          (select count(concert.kid) concert            inner join ticket on concert.kid = ticket.kid type = 'vip') >       (select count(concert.kid) concert            inner join ticket on concert.kid = ticket.kid type != 'vip')

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