MySql从两个表中选择多个表，并将它们的结果连接到第三个表

我有三张桌子：球员，球员档案，比赛。玩家和玩家档案表的结构完全相同

在玩家和玩家档案中，我们有玩家ID和名字

在比赛中，我们有一排：

RaceID、Record1PlayerID、Record2PlayerID、Record3PlayerID、Record4PlayerID和Record5PlayerID

任务是选择整个Races表，但它应该返回其名称，而不是球员ID字段

e、 g:

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您的数据结构有两个问题。首先，你应该为每场比赛中的球员准备一个单独的表格，每个球员/比赛组合一行。将它们放在一行的不同列中是个坏主意

第二个问题是将名称放在两个不同的表中。从您的问题中，我无法判断

播放器

表和

播放器存档

表是否都是必需的。因此，我假设不需要存档

解决方案是从races表连接到包含玩家信息的表：

select r.*,
       p1.name as name1,
       p2.name as name2,
       p3.name as name3,
       p4.name as name4,
       p5.name as name5
from races r left outer join
     players p1
     on r.record1playerid = p1.playerid left outer join
     players p2
     on r.record1playerid = p2.playerid left outer join
     players p3
     on r.record1playerid = p3.playerid left outer join
     players p4
     on r.record1playerid = p4.playerid left outer join
     players p5
     on r.record1playerid = p5.playerid left outer join

如果数据确实在

Players

和

PlayersArchive

中，则

Players

可能需要：

     (select distinct playerid, name from ((select p.* from players) union all (select pa.* from playersarchive)) t) p1 . . .

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这将两个表组合在一起以查找名称。

这将仅演示一个可能的解决方案，以满足您的要求

Select RaceId, p1.Name AS Name1 From Races AS r
Left Join (
    Select * From Players 
    Union Select * From PlayersArchive
) AS p1 On r.Record1PlayerID = p1.PlayerID;

您应该在查询中再重复4次左连接，以获得所有5个名称。

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请注意，对于大数据，这可能需要很长时间才能执行。

如果玩家和玩家档案表基本相同，那么为什么要将它们分开呢？（按照@fancyPants的说法…）除非您需要大量数据（即使是这样，也有一些方法可以进行扩展—您是否记得在连接中使用的字段中添加索引？），通过将播放器拆分到单独的存档表中，您将使事情变得更加复杂。

result:
1     Jack     Jhon     NULL     NULL     NULL

select r.*,
       p1.name as name1,
       p2.name as name2,
       p3.name as name3,
       p4.name as name4,
       p5.name as name5
from races r left outer join
     players p1
     on r.record1playerid = p1.playerid left outer join
     players p2
     on r.record1playerid = p2.playerid left outer join
     players p3
     on r.record1playerid = p3.playerid left outer join
     players p4
     on r.record1playerid = p4.playerid left outer join
     players p5
     on r.record1playerid = p5.playerid left outer join

     (select distinct playerid, name from ((select p.* from players) union all (select pa.* from playersarchive)) t) p1 . . .

Select RaceId, p1.Name AS Name1 From Races AS r
Left Join (
    Select * From Players 
    Union Select * From PlayersArchive
) AS p1 On r.Record1PlayerID = p1.PlayerID;