프로그래머스 고득점 키트_ JOIN_MYSQL
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1. 없어진 기록찾기
select aout.ANIMAL_ID, aout.NAME
from ANIMAL_OUTS as aout
left join ANIMAL_INS as ain
on aout.ANIMAL_ID = ain.ANIMAL_ID
where ain.ANIMAL_ID is null
2. 있었는데요 없었습니다.
select ain.ANIMAL_ID, ain.NAME
from ANIMAL_INS as ain
join ANIMAL_OUTS as aout
on ain.ANIMAL_ID = aout.ANIMAL_ID
where ain.DATETIME > aout.DATETIME
order by ain.DATETIME
3. 오랜 기간 보호한 동물
select ain.NAME, ain.DATETIME
from ANIMAL_INS as ain
left join ANIMAL_OUTS as aout
on ain.ANIMAL_ID = aout.ANIMAL_ID
where aout.NAME is null and ain.NAME is not null
order by ain.DATETIME
limit 3
4. 보호소에서 중성화한 동물
select ain.ANIMAL_ID, ain.ANIMAL_TYPE, ain.NAME
from ANIMAL_INS as ain
inner join ANIMAL_OUTS as aout
on ain.ANIMAL_ID = aout.ANIMAL_ID
where ain.SEX_UPON_INTAKE like "Intact%"
and aout.SEX_UPON_OUTCOME like "Neutered%"
or ain.SEX_UPON_INTAKE like "Intact%"
and aout.SEX_UPON_OUTCOME like "Spayed%"
order by ain.ANIMAL_ID