121. Qator taqqoslash (a, b) = (...)

Avval eng katta summali bitta sotuvni toping. So'ng o'sha sotuv bilan

bir xil (shahar, mahsulot) juftligiga ega barcha sotuvlarni chiqaring

(eng kattasining o'zi ham kiradi).

Buni qator konstruktori bilan yozing:

WHERE (city, product) = (SELECT city, product FROM ... ORDER BY ... LIMIT 1)

Ikkita ustunni ikkita alohida ichki so'rov bilan emas, bitta ichki so'rov

bilan taqqoslash shu usulning mohiyati.

Ustunlar: id, city, product, amount.

Saralash: amount kamayish, keyin id o'sish.

sales: id INT PK, city VARCHAR, product VARCHAR, amount NUMERIC(12,2)

Jadval: sales