생각해우소

DROP TABLE STUDENTS;

-STUDENTS 테이블 삭제-

CREATE TABLE STUDENTS

(

  "SID" VARCHAR2(30),

  "PWD" VARCHAR2(30) ,

  "NAME" VARCHAR2(30),

  "GENDER" VARCHAR2(8),

  "AGE" NUMBER ,

  "BIRTHDAY" CHAR(10),

  "MAJOR" VARCHAR2(50),

  "ADDRESS" NVARCHAR2(300),

  "PHONE" VARCHAR2(13),

  "SSN" CHAR(14),

  "IP" VARCHAR(15),

  "REGDATE" DATE

);

STUDENTS 테이블 생성

ALTER TABLE STUDENTS ADD "TABLE" VARCHAR2(30);

ALTER TABLE STUDENTS DROP COLUMN "TABLE" ;

ALTER TABLE STUDENTS MODIFY GENDER VARCHAR(6);

-STUDENTS 테이블에 VARCHAR2(30)자료형의 "TABLE" 추가

-STUDENTS 테이블에 "TABLE"컬럼 삭제

-STUDENTS 테이블에 GENDER컬럼을 VARCHAR2(6)자료형으로 변경

ROLLBACK; --INSERT , DELETE, UPDATE 실행후 반드시해줘야함. 

나에게는 보이지만 남은 조회해도 보이지 않을 수 있음.

COMMIT;

SELECT * FROM STUDENTS;  --데이터 불러오기  = AS 별칭으로 불러오기

SELECT AGE-25 FROM STUDENTS;  --데이터 불러오기

SELECT 'A'+10 AS 더하기 FROM DUAL;

SELECT '홍길동' || '(' || '28' || ')' AS 더하기 FROM DUAL;

INSERT INTO STUDENTS VALUES('슈퍼 조현상', '111');  --입력후에 롤백,커밋을 선택

DELETE STUDENTS WHERE SID='슈퍼조현상';

UPDATE STUDENTS SET AGE='1' WHERE SID='슈퍼 조현상';

SELECT * FROM STUDENTS WHERE GENDER IS NULL; --IS NOT NULL도 있음

SELECT * FROM STUDENTS WHERE GENDER != '남성';

SELECT * FROM STUDENTS WHERE AGE < 20;

SELECT * FROM STUDENTS WHERE AGE<=20 AND AGE>=5; 

SELECT * FROM STUDENTS WHERE AGE BETWEEN 5 AND 20; --위와 같은 결과

SELECT * FROM STUDENTS WHERE AGE=1 OR AGE=15 OR AGE=20;

SELECT * FROM STUDENTS WHERE AGE () IN (1, 15, 20); --위와 같은 결과, 반대는 NOT을 ()에 넣어주면 된다.

ROLLBACK;

COMMIT;

SELECT * FROM STUDENTS;  --데이터 불러오기

INSERT INTO STUDENTS VALUES('슈퍼 조현상', '111');  --입력후에 롤백,커밋을 선택

DELETE STUDENTS WHERE SID='';

UPDATE STUDENTS SET NAME='조현상', GENDER='여자' WHERE SID='슈퍼 조현상';

DROP TABLE STUDENTS;

CREATE TABLE STUDENTS188

(

  "SID" VARCHAR2(30),

  "PWD" VARCHAR2(30) ,

  "NAME" VARCHAR2(30),

  "GENDER" VARCHAR2(8),

  "AGE" NUMBER ,

  "BIRTHDAY" CHAR(10),

  "MAJOR" VARCHAR2(50),

  "ADDRESS" NVARCHAR2(300),

  "PHONE" VARCHAR2(13),

  "SSN" CHAR(14),

  "IP" VARCHAR(15),

  "REGDATE" DATE

);

ALTER TABLE STUDENTS188 ADD CITY VARCHAR2(30);

ALTER TABLE STUDENTS188 DROP COLUMN CITY ;

ALTER TABLE STUDENTS188 MODIFY REGDATE TIMESTAMP ;