2nd week for SQL

Group by name : make one group have same name.

Select name(범주 별로 세어주고 싶은 필드명), count(*) from users(테이블)

group by name(범주 별로 세어주고 싶은 필드명)

Select week, min(likes) from checkins

group by week -> week별 likes(최소값을 알고 싶은 필드명) 최소값

Select week, max(likes) from checkins

group by week -> 최대값

Select week, avg(likes) from checkins

group by week -> 평균값

Select week, sum(likes) from checkins

group by week -> 합계

Order by : sort by your need

Select * from users

order by name->오름차순

Select name, count(*) from users

group by name

order by count(*) desc;->내림차순

Order to operate query : from -> group by -> select(name, count(*))-> order by

Select payment_method, count(*) from orders

where course_title = ‘웹개발 종합반’

Group by payment_method

Order to operate query : from -> where -> group by -> select

We should know order to operate query to avoid error.

Example)

Select name, count(*) from users

where email like ‘%gmail.com’

group by name