-- sql01

select max(iznos) as maksiznos from transakcii as t

-- sql02

select t.br_smetka, t.br_transakcija from transakcii as t
where t.iznos = (
    select max(iznos) as maksiznos from transakcii
)

-- sql03

select b.id_banka, b.naziv_banka, s.br_smetka, t.br_transakcija, t.iznos from banki as b
left join smetki as s on b.id_banka=s.id_banka
left join transakcii as t on t.br_smetka=s.br_smetka

-- sql04

-- my subquery
select max(subq.inmax) as maksiznos from (
    select s.id_banka, (
        select max(iznos) as maksiznos from transakcii as t
        where t.br_smetka = s.br_smetka
    ) as inmax from smetki as s
) as subq
where subq.id_banka=1

-- final
select b.id_banka, b.naziv_banka, (
    select max(subq.inmax) as maksiznos from (
        select s.id_banka, (
            select max(iznos) as maksiznos from transakcii as t
            where t.br_smetka = s.br_smetka
        ) as inmax from smetki as s
    ) as subq
    where subq.id_banka=b.id_banka
) from banki as b
left join smetki as s on b.id_banka=s.id_banka
left join transakcii as t on t.br_smetka=s.br_smetka


-- sql05

select b.id_banka, b.naziv_banka, s.br_smetka, t.br_transakcija, t.iznos, v.ime_vraboten from banki as b
left join smetki as s on b.id_banka=s.id_banka
left join transakcii as t on t.br_smetka=s.br_smetka
left join odgovoren as o on o.br_smetka=t.br_smetka and o.br_transakcija=t.br_transakcija
left join vraboteni as v on v.id_banka=o.id_banka and v.id_vraboten=o.id_vraboten

-- sql06

-- my subquery
select v.ime_vraboten from transakcii as t
inner join odgovoren as o on o.br_smetka=t.br_smetka and o.br_transakcija=t.br_transakcija
inner join vraboteni as v on v.id_banka=o.id_banka and v.id_vraboten=o.id_vraboten
where o.id_banka=b.id_banka and t.iznos=subq.maksiznos

-- final
select b.naziv_banka, (
    select v.ime_vraboten from transakcii as t
    inner join odgovoren as o on o.br_smetka=t.br_smetka and o.br_transakcija=t.br_transakcija
    inner join vraboteni as v on v.id_banka=o.id_banka and v.id_vraboten=o.id_vraboten
    where o.id_banka=b.id_banka and t.iznos=subq.maksiznos
) from banki as b
inner join (
    select b.id_banka, b.naziv_banka, (
        select max(subq.inmax) as maksiznos from (
            select s.id_banka, (
                select max(iznos) as maksiznos from transakcii as t
                where t.br_smetka = s.br_smetka
            ) as inmax from smetki as s
        ) as subq
        where subq.id_banka=b.id_banka
    ) from banki as b
    left join smetki as s on b.id_banka=s.id_banka
    left join transakcii as t on t.br_smetka=s.br_smetka
) as subq on subq.id_banka=b.id_banka