[생활코딩] 3일차 - 2. CRUD : Read

https://youtu.be/FCnJH6fLc64

 

SELECT FROM

- SELECT ___ FROM ; 사이에 Read 하고 싶은 컬럼명만 입력

SELECT id, title, created, author FROM topic;
+----+------------+---------------------+--------+
| id | title      | created             | author |
+----+------------+---------------------+--------+
|  1 | MySQL      | 2022-04-17 19:27:40 | egoing |
|  2 | ORACLEL    | 2022-04-17 19:29:30 | egoing |
|  3 | SQL Server | 2022-04-17 19:43:49 | duru   |
|  4 | PostgreSQL | 2022-04-17 19:44:56 | taeho  |
|  5 | MongoDB    | 2022-04-17 19:45:47 | egoing |
+----+------------+---------------------+--------+

- 전체 보고 싶을 때는

SELECT * FROM topic;

 

조건 : WHERE

SELECT id, title, created, author FROM topic WHERE author='egoing';
+----+---------+---------------------+--------+
| id | title   | created             | author |
+----+---------+---------------------+--------+
|  1 | MySQL   | 2022-04-17 19:27:40 | egoing |
|  2 | ORACLEL | 2022-04-17 19:29:30 | egoing |
|  5 | MongoDB | 2022-04-17 19:45:47 | egoing |
+----+---------+---------------------+--------+

- WHERE : 조건

→ topic에서(FROM) id, title, created, author 열을 선택해서 보여줘(SELECT)

그런데 조건!(WHERE) author이 'egoing'

 

정렬 : ORDER BY

SELECT id, title, created, author FROM topic WHERE author='egoing' ORDER BY id DESC;
+----+---------+---------------------+--------+
| id | title   | created             | author |
+----+---------+---------------------+--------+
|  5 | MongoDB | 2022-04-17 19:45:47 | egoing |
|  2 | ORACLEL | 2022-04-17 19:29:30 | egoing |
|  1 | MySQL   | 2022-04-17 19:27:40 | egoing |
+----+---------+---------------------+--------+

- id를 기준으로 정렬해서(ORDER BY) 보여줘. 내림차순으로(DESC)

 

개수 제한 : LIMIT

SELECT id, title, created, author FROM topic WHERE author='egoing' ORDER BY id DESC LIMIT 2;
+----+---------+---------------------+--------+
| id | title   | created             | author |
+----+---------+---------------------+--------+
|  5 | MongoDB | 2022-04-17 19:45:47 | egoing |
|  2 | ORACLEL | 2022-04-17 19:29:30 | egoing |
+----+---------+---------------------+--------+

- 2개만 보여줘 (LIMIT 2)