모든 컬럼 조회
select * from users
필요한 컬럼 조회
select user_id, name from users
select * from 테이블명
where 컬럼 조회 조건
group by 컬럼 그룹 조건
order by 컬럼 순서 조건
select * from orders
where payment_method = "kakaopay"
select * from users
where name = "김%"
select * from orders
where payment_method = "kakaopay"
limit 5
select distinct(payment_method) from orders
select count(*) from orders
select payment_method, count(*) from orders
where course_title = "웹개발 종합반"
group by payment_method
asc : 오름차순, desc : 내림차순
select * from users
order by created_at desc
A와 B 테이블 모두에 있는 레코드만 조회
select o.payment_method, round(AVG(p.point)) from point_users p
inner join orders o on p.user_id = o.user_id
group by o.payment_method