[생활코딩] 3일차 - 3. CRUD : Update, Delete

https://youtu.be/pNINXzXaWWM

 

* 공통점 : WHERE 꼭 해줘야한다 ..

안하면 전체가 U, D 됨

 

UPDATE ... SET ... WHERE ... ;

UPDATE topic SET description = 'Oracle is ...', title='Oracle' WHERE id=2;

- topic을 수정(UPDATE)

- 컬럼명 description을 Oracle is ... 로, title을 Oracle로 변경(SET)

- (중요!!!!!) 조건(WHERE) : id가 2인 행을

 └ WHERE 안하면 모든 행이 바뀜 ...

 

결과

SELECT * FROM topic;
+----+------------+-------------------+---------------------+--------+---------------------------+
| id | title      | description       | created             | author | profile                   |
+----+------------+-------------------+---------------------+--------+---------------------------+
|  1 | MySQL      | MySQL is ...      | 2022-04-17 19:27:40 | egoing | developer                 |
|  2 | Oracle     | Oracle is ...     | 2022-04-17 19:29:30 | egoing | developer                 |
|  3 | SQL Server | SQL Server is ... | 2022-04-17 19:43:49 | duru   | data administrator        |
|  4 | PostgreSQL | PostgreSQL is ... | 2022-04-17 19:44:56 | taeho  | data scientist, developer |
|  5 | MongoDB    | MongoDB is ...    | 2022-04-17 19:45:47 | egoing | developer                 |
+----+------------+-------------------+---------------------+--------+---------------------------+

 

DELETE FROM ... WHERE ... ;

DELETE FROM topic WHERE id = 5;

- topic에서 삭제함(DELETE)

- (중요!!!) 조건(WHERE) : id가 5인 행을

 └ WHERE 안쓰면 전체 삭제됨

 

결과

SELECT * FROM topic;
+----+------------+-------------------+---------------------+--------+---------------------------+
| id | title      | description       | created             | author | profile                   |
+----+------------+-------------------+---------------------+--------+---------------------------+
|  1 | MySQL      | MySQL is ...      | 2022-04-17 19:27:40 | egoing | developer                 |
|  2 | Oracle     | Oracle is ...     | 2022-04-17 19:29:30 | egoing | developer                 |
|  3 | SQL Server | SQL Server is ... | 2022-04-17 19:43:49 | duru   | data administrator        |
|  4 | PostgreSQL | PostgreSQL is ... | 2022-04-17 19:44:56 | taeho  | data scientist, developer |
+----+------------+-------------------+---------------------+--------+---------------------------+