1. Aggregation & Grouping

Aggregation

SELECT SUM(CTIME), MIN(CTIME), MAX(CTIME), COUNT(CTIME)
FROM COURSE;

Grouping

select pedpt count(*)
from pogt

2. Subqueries

여러가지 조건이 들어가는것. 쿼리안에 쿼리가 하나더~!!

(아래 두개의 코드는 같은 결과를 도출하지만 작성법이 조금 다르다.)

select c1.cname
from course c1, course c2
where c1.ctime >= c2.ctime and c2.cname='OS';

select cname
from course
where ctime >= (select ctime from course where cname = 'OS');

Operators

• Single Row - = , >, ≥, <, ≤, <>(! =과 같은의미), ! =
• Multiple Row - IN, NOT IN, ANY, ALL, EXISTS

3. Views