1. SQL 연산 순서 FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY DML(Data Manipulation Language) : INSERT, SELECT, UPDATE, DELETE DDL(Data Definition Language) : CREATE, ALTER, MODIFY, DROP TCL(Transaction Control Language) : ROLLBACK, COMMIT DCL(Data Control Language) : GRANT, REVOKE 2. DISTINCT : 어떤 컬럼 값들의 중복을 제거한 결과를 출력 SELECT DISTINCT COL FROM TABLE; 유일한 값들 출력 SELECT DISTINCT COL1, COL2 FRO..