-- 테이블 기준 foreign key 확인
select * from information_schema.table_constraints where table_name = 'master_company';
-- Foreign Key 삭제
ALTER TABLE cm_db.master_department DROP FOREIGN KEY master_department_ibfk_1;
ALTER TABLE cm_db.master_department DROP FOREIGN KEY master_department_ibfk_2;
-- Foreign Key 복구
ALTER TABLE cm_db.master_department ADD CONSTRAINT master_department_ibfk_1 FOREIGN KEY (department_leader) REFERENCES master_employee (emp_id);
ALTER TABLE cm_db.master_department ADD CONSTRAINT master_department_ibfk_2 FOREIGN KEY (company_id) REFERENCES master_company (company_id);
alter table cm_db.master_company modify column company_id varchar(20) character set utf8 collate utf8_general_ci;
alter table 테이블명' modify column 컬럼명 데이터타입 character set 캐릭터셋 collate 하위캐릭터셋
ex)
alter table cm_db.master_company modify column company_name varchar(100) character set utf8mb4 collate utf8mb4_general_ci;
* 참고자료