<SQL 명령문 개괄>

1) 순서 정렬 문제

FROM-WHERE-GROUP BY -HAVING-SELECT-ORDER-BY

2) 종류

DML- SELECT, INSERT,DELET,UPDATE

DDL-ALTER,CREATE,MODIFY,DROP

TCL- ROLLBACK,COMMIT

DCL- GRANT,REVOKE

<SELECT>

DISTNCT(집약)→10,10,20,20,30→10,20,30

<DISTINCT DEPNO,MGR>

=GROUP BY(DEPNO,MGR)

AS-ALIAS

SELECT→1.생략가능 2. 컬럼명에 띄어쓰기 (”직원번호”)

FROM→AS 사용불가