同一个表的两个外键.我该如何编写这个SELECT语句？

Question

用户表

user_id    username    thumb_id    fullimage_id
1          jprescott   14          15
2          lpausch     18          19

图像表

image_id    path
14          jprescott/small.jpg
15          jprescott/big.jpg
16          msamuels/small.jpg
17          msamuels/big.jpg
18          lpausch/small.jpg
19          lpausch/big.jpg

现在,如何编写SELECT语句来检索具有thumb和fullimage路径的用户？问题是有两个同一个表的外键.

Answer 1

你做两个连接:

SELECT u.username, i1.path AS thumb, i2.path AS full
  FROM users AS u
    JOIN images AS i1 ON u.thumb_id = i1.image_id
    JOIN images AS i2 ON u.fullimage_id = i2.image_id