codecamedy의 learn SQL 1. Manipulation

 

https://www.codecademy.com/learn/learn-sql

SQL Tutorial: Learn SQL For Free | Codecademy

 

Learn how to use SQL to access, create, and update data stored in a database.

 

딱 봐도 까먹을 각이라 적어놓는다.

 

1. SELECT

SELECT * FROM celebs;

2. CREATE

CREATE TABLE celebs (
   id INTEGER, 
   name TEXT, 
   age INTEGER
);

3. INSERT

INSERT INTO celebs (id, name, age) 
VALUES (1, 'Justin Bieber', 22);

4. ALTER

ALTER TABLE celebs 
ADD COLUMN twitter_handle TEXT;

alter로 table에 새로운 column을 추가할 수 있다.

 

5. UPDATE

UPDATE celebs 
SET twitter_handle = '@taylorswift13' 
WHERE id = 4;

6. DELETE

DELETE FROM celebs 
WHERE twitter_handle IS NULL;

7. Constraints

CREATE TABLE celebs (
   id INTEGER PRIMARY KEY, 
   name TEXT UNIQUE,
   date_of_birth TEXT NOT NULL,
   date_of_death TEXT DEFAULT 'Not Applicable'
);

column에서 type을 정의한 뒤 추가 제약/정보.

 

 

• CREATE TABLE creates a new table.
• INSERT INTO adds a new row to a table.
• SELECT queries data from a table.
• ALTER TABLE changes an existing table.
• UPDATE edits a row in a table.
• DELETE FROM deletes rows from a table.