[Hacker Rank SQL 정복기] Basic Select - ①

🥇 : Revising the Select Query I

❓ Question

❗ Answer

SELECT * FROM city WHERE population > 100000 AND countrycode = 'USA'

📌 Discussion

• 모든 column은 *로 호출 가능

🥇 : Revising the Select Query II

❓ Question

❗ Answer

SELECT name FROM city WHERE population > 120000 AND countrycode = 'USA'

📌 Discussion

• 특정 column을 호출할 때는 대소문자 구분없이, 따옴표없이 기입가능하나,
  WHERE절의 특정 키워드(USA)는 대소문자 구분은 없지만 따옴표는 있어야한다.
  (따옴표 없을 시 런타임 에러 발생)

🥇 : Select All

❓ Question

❗ Answer

SELECT * FROM city

📌 Discussion

• 모든 column을 불러올 때는 *로 호출

🥇 : Select By ID

❓ Question

❗ Answer

SELECT * FROM city WHERE id = '1661'

📌 Discussion

• WHERE절 사용

🥇 : Japanese Cities' Attributes

❓ Question

❗ Answer

SELECT * FROM city WHERE countrycode = 'JPN'

📌 Discussion

• WHERE절 사용

🥇 : Japanese Cities' Names

❓ Question

❗ Answer

SELECT name FROM city WHERE countrycode = 'JPN'

📌 Discussion

• WHERE절 사용

🥇 : Weather Observation Station 1

❓ Question

❗ Answer

SELECT city, state FROM station

📌 Discussion

• 복수 column 호출