DATABASE
- 계층형 ( tree )
- 네트워크형 ( owner / member )
- 관계형 ( relation ) => 집합 연산 / 관계 연산
DATABASE MANAGEMENT SYSTEM
Structured Query Language
DDL ( Data Definition Language )
CREATE, ALTER, DROP, RENAME, TRUNCATE
[ALTER/RENAME] ALTER TABLE RENAME TO
[ALTER] ALTER TABLE ADD (age number(2) DEFAULT 1)
[ALTER] ALTER TABLE MODIFY (ename varchar(20) NOT NULL) => type 변경 x
[ALTER] ALTER TABLE DROP COLUMN age;
[ALTER] ALTER TABLE RENAME COLUMN age to old;
DML ( Data Manipulation Language )
- INSERT, UPDATE, DELETE, SELECT
DCL ( Data Control Language )
- GRANT, REVOKE
TCL ( Transaction Control Language )
- COMMIT, ROLLBACK, SAVEPOINT
ACID
constraint <fKeyname> foreign key (keyname) references table(key)
ON DELETE CASCADE