LEFT_JOIN

LEFT JOIN操作

• From 後的資料表的列會全部顯示

LEFT JOIN範例

• 匯入albumsAndartist.sql

範例1

SELECT
   artists.ArtistId, 
   AlbumId
FROM
   artists
LEFT JOIN albums ON
   albums.ArtistId = artists.ArtistId
ORDER BY
   AlbumId;

範例2

SELECT
   artists.ArtistId
   , AlbumId
FROM
   artists
LEFT JOIN albums ON
   albums.ArtistId = artists.ArtistId
WHERE
   AlbumId IS NULL;