SQL 문제풀이 복습
SELECT customer_number
FROM orders
GROUP BY 1
ORDER BY Count(*) DESC
LIMIT 1;
SELECT name,
population,
area
FROM world
WHERE area >= 3000000
OR population >= 25000000;
SELECT class
FROM courses
GROUP BY 1
HAVING Count(*) >= 5;
오늘은 다 easy 문제만 걸려서 빠르게 끝!