sql

가져오기, join

SELECT article.id, article.title, 
       category.name,
       image.file, image.alt

  FROM article 
  JOIN category   ON article.category_id = category.id
  LEFT JOIN image ON article.image_id    = image.id

 WHERE article.category_id = 3 
   AND article.published   = 1
 ORDER BY article.id DESC;

 

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결합하기, AS (앨리어스)

SELECT CONCAT(forename, ' ', surname) AS author 
  FROM member;

null 대체 

SELECT COALESCE(picture, forename, 'friend') AS profile
  FROM member;

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추가

INSERT INTO image (file, alt)
VALUES ('bicycle.jpg', 'Photo of bicycle'),
       ('ghost.png',   'Illustration of ghost'),
       ('stamp.jpg',   'Polite Society stamp');

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업데이트

UPDATE category 
   SET navigation = 0
 WHERE navigation = 1;

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삭제 

DELETE FROM category 
 WHERE id = 5;