문제
MySQL
: 대소문자 구분하지 않아도 됨
내가 작성한 정답1 - like
select distinct city
from station
where city not like 'I%' and city not like 'E%' and city not like 'A%' and city not like 'O%' and city not like 'U%';
내가 작성한 정답2 - 정규표현식
select distinct city
from station
where city not regexp '^[aeiou]';
내가 작성한 정답3 - substring, substr 둘 다 사용가능
select distinct city
from station
where substr(city,1,1) not in ('a','e','i','o','u');
select distinct city
from station
where substring(city,1,1) not in ('a','e','i','o','u');
내가 작성한 정답4 - left
select distinct city
from station
where left(city,1) not in ('a','e','i','o','u');
Oracle
: 대소문자 구분 필요
내가 작성한 정답1 - like
: 도시의 첫글자는 대문자
select distinct city
from station
where city not like 'I%'
and city not like 'E%'
and city not like 'A%'
and city not like 'O%'
and city not like 'U%';
내가 작성한 정답2 - 정규표현식 regexp_like
select distinct city
from station
where not regexp_like(lower(city),'^[aeiou]');
내가 작성한 정답3 - substr
select distinct city
from station
where substr(lower(city),1,1) not in ('a','e','i','o','u');
MS SQL Server - MySQL과 유사
: 대소문자 구분 x
내가 작성한 정답1 - like
select distinct city
from station
where city not like 'I%' and city not like 'E%' and city not like 'A%' and city not like 'O%' and city not like 'U%';
내가 작성한 정답2 - like2
select distinct city
from station
where city not like '[aeiou]%';
내가 작성한 정답3 - substring
select distinct city
from station
where substring(city,1,1) not in ('a','e','i','o','u');
내가 작성한 정답4 - left
select distinct city
from station
where left(city,1) not in ('a','e','i','o','u');
DB2 - Oracle과 유사
내가 작성한 정답1 - like
select distinct city
from station
where city not like 'I%' and city not like 'E%' and city not like 'A%' and city not like 'O%' and city not like 'U%';
내가 작성한 정답2 - substr
select distinct city
from station
where substr(lower(city),1,1) not in ('a','e','i','o','u');
정리!
DBMS | 문자추출 | left 유무 | 정규표현식 |
MS SQL Server | substring - 음수지원 X | o | x → like로 표현가능 |
MySQL | substring - 음수 지원 | o | o → regexp |
Oracle | substr - 음수 지원 | x | o → regexp_like(colunm,정규식) |
DB2 | substr - 음수 지원 X | x | x → substr로 표현가능 |
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