[SQL] SQL 학습일지 04

PRIMARY KEY / FOREIGN KEY 예제

1. primary key = study_id, foreign key = patient_id (person의 pid) 테이블 생성

create table study
    -> (
    -> study_id int Not NULL,
    -> study_date date,
    -> study_time time,
    -> patient_id int
    -> )
    -> ;

alter table study
    -> add primary key (study_id);

alter table study
    -> add constraint FK_study foreign key (patient_id) references person (pid);

desc study;

show create table study;

2. 생성한 테이블의 primary key 삭제
   
   
   

alter table study
   -> drop primary key;

desc study;

3. 생성한 테이블의 foreign key 삭제

alter table study
    -> drop foreign key FK_study;

desc study;

show craete table study;

4. study 테이블의 patient_id 를 person 테이블의 pid 와 연결된 foreign key로 등록
   
   
   

alter table study
    -> add foreign key (patient_id) references person (pid);

show create table study;

5. study 테이블의 study_id 를 primary key 로 등록

alter table study
    -> add primary key (study_id);

desc study;