一条语句中的两个内部联接产生0个结果

Question

当运行多个内部连接时，我得到的结果为零

代码如下：

SELECT doubles_ladder.*, players.*
from doubles_ladder
  JOIN players on doubles_ladder.player_number = players.Player_number
  JOIN players AS play ON doubles_ladder.player_number2 = players.Player_number

我知道这两个表中都有信息，这是奇怪的，它没有产生结果。

非常感谢任何帮助。

Answer 1

您没有使用为第二个联接表(play)设置的别名。我将在以下方面进行更改：

    SELECT doubles_ladder.*, player1.*, player2.*
    FROM doubles_ladder
        INNER JOIN players AS player1
            ON (doubles_ladder.player_number = player1.Player_number)
        INNER JOIN players AS player2
            ON (doubles_ladder.player_number2 = player2.Player_number)