SQL 퀘스트

> 정답

34. SELECT gender,
    COUNT(1) AS num_patients
    FROM patients
    GROUP BY gender;
35. SELECT COUNT(1) AS over_40
    FROM patients
    WHERE birth_date <= DATE_SUB(CURDATE(), INTERVAL 40 YEAR);
36. SELECT *
    FROM patients
    WHERE last_visit_date <= DATE_SUB(CURDATE(), INTERVAL 1 YEAR);
37. (내가 쓴 코드)
    SELECT COUNT(1) AS born_in_80s
    FROM patients
    WHERE birth_date LIKE '%198%';
38. (답안, 확실히 80년대생만 선택하겠다는 작성의도가 잘 보여서
    가독성이 좋다)
    SELECT COUNT(1) AS born_in_80s
    FROM patients
    WHERE birth_date BETWEEN '1980-01-01' AND '1989-12-31'