mysql - MySQL：将两行合二为一

Question

用户表：

id  |   win  |   lose
0   |   1    |   2
1   |   2    |   8

游戏桌：

id  |  user1  |  user2  |  data
0   |  0      |  1      |  'some text'

DB 用于简单的多人游戏。我需要一个查询来获取两个用户的用户 2、数据和输赢数据。这在 MySQL 中可能吗？任何帮助将不胜感激。

Answer 1

你必须两次这样JOIN的桌子：users

SELECT
  u1.win  AS win1,
  u1.lose AS lose1,
  u2.win  AS win2,
  u2.lose AS lose2,
  ...
FROM games g
INNER JOIN users u1 ON g.user1 = u1.id
INNER JOIN users u2 ON g.user2 = u2.id

Answer 2

您可以加入users表两次：

SELECT
    games.user2 AS user2_id
    games.data AS games_data
    user1.win AS user1_win,
    user1.lose AS user1_lose,
    user2.win AS user2_win,
    user2.lose AS user2_lose
FROM games
JOIN users AS user1 ON user1.id = games.user1
JOIN users AS user2 ON user2.id = games.user2
WHERE games.id = ...