SQL Datetime

1. DATETIME & STR
   """
   DATE_FORMAT(STR_TO_DATE(date, '%Y%m%d'),'%Y-%m-%d ')
   """

2. DATETIME DIFFERENCE
   https://school.programmers.co.kr/learn/courses/30/lessons/59411

select t.id, t.nm
from (SELECT ins.animal_id id
              ,ins.name nm
              ,row_number() over (order by outs.datetime-ins.datetime desc) idx
        from animal_ins ins
        inner join animal_outs outs
        on ins.animal_id = outs.animal_id) t
where t.idx <= 2

3. DATIMETIME > DATE
   https://school.programmers.co.kr/learn/courses/30/lessons/59414

SELECT animal_id, name, date_format(datetime, "%Y-%m")
from animal_ins
order by animal_id asc

4. DATETIME RANK : 오랜 기간 보호한 동물(1)(2)
   https://school.programmers.co.kr/learn/courses/30/lessons/59044

select t.name, t.datetime
from (
    SELECT ins.name name
          ,ins.datetime datetime
          ,row_number() over (order by ins.datetime asc) idx
    from animal_ins ins
    left outer join animal_outs outs
    on ins.animal_id = outs.animal_id
    where outs.animal_id is null) t
where t.idx <= 3

select t.id, t.nm
from (SELECT ins.animal_id id
              ,ins.name nm
              ,row_number() over (order by outs.datetime-ins.datetime desc) idx
        from animal_ins ins
        inner join animal_outs outs
        on ins.animal_id = outs.animal_id) t
where t.idx <= 2