Mysql 同一表上的多个联接
到目前为止，我有这个Mysql 同一表上的多个联接,mysql,sql,Mysql,Sql,到目前为止，我有这个 SELECT p1.player_id, p1.real_name, p2.player_id, p2.real_name, -> m.scoreA, m.scoreB -> FROM matches m -> JOIN players p1 ON p1.player_id = m.playerA -> JOIN players p2 ON p2.player_id = m.playerB; +-------
SELECT p1.player_id, p1.real_name, p2.player_id, p2.real_name,
-> m.scoreA, m.scoreB
-> FROM matches m
-> JOIN players p1 ON p1.player_id = m.playerA
-> JOIN players p2 ON p2.player_id = m.playerB;
+-----------+------------------------------------+-----------+------------------------------------+--------+--------+
| player_id | real_name | player_id | real_name | scoreA | scoreB |
+-----------+------------------------------------+-----------+------------------------------------+--------+--------+
| 19 | Seong Hun Choi | 1 | Dong Nyoung Lee | 0 | 2 |
| 38 | Yun Sik Choi | 1 | Dong Nyoung Lee | 0 | 2 |
| 160 | Lei Wang | 1 | Dong Nyoung Lee | 0 | 2 |
| 3 | Seung Hyun Lee | 1 | Dong Nyoung Lee | 0 | 2 |
| 45 | Min Chul Kim | 1 | Dong Nyoung Lee | 0 | 2 |
| 23 | Sasha Hostyn | 1 | Dong Nyoung Lee | 2 | 4 |
| 52 | Juan Moreno Duran | 1 | Dong Nyoung Lee | 2 | 3 |
| 18 | Kang Dong Hyun | 1 | Dong Nyoung Lee | 2 | 1 |
| 22 | Jae Duck Lim | 1 | Dong Nyoung Lee | 1 | 2 |
| 108 | Jérémy Vansnick | 1 | Dong Nyoung Lee | 1 | 2 |
成员表SELECT p1.player_id, p1.real_name, p2.player_id, p2.real_name,
m.scoreA, m.scoreB, mem1.player, mem2.player
FROM matches m
JOIN players p1 ON p1.player_id = m.playerA
JOIN members mem1 ON mem1.player = p1.player_id
JOIN players p2 ON p2.player_id = m.playerB
JOIN members mem2 ON mem2.player = p2.player_id;
SELECT p1.player_id, p1.real_name, p2.player_id, p2.real_name,
m.scoreA, m.scoreB, mem1.player, mem2.player
FROM matches m
JOIN players p1 ON p1.player_id = m.playerA
JOIN members mem1 ON mem1.player = m.playerA
JOIN players p2 ON p2.player_id = m.playerB
JOIN members mem2 ON mem2.player = m.playerB;
+-----------+------------------------------------+-----------+------------------------------------+--------+--------+
| player_id | real_name | player_id | real_name | scoreA | scoreB | member1 member2
+-----------+------------------------------------+-----------+------------------------------------+--------+--------+
| 19 | Seong Hun Choi | 1 | Dong Nyoung Lee | 0 | 2 |
| 38 | Yun Sik Choi | 1 | Dong Nyoung Lee | 0 | 2 |
| 160 | Lei Wang | 1 | Dong Nyoung Lee | 0 | 2 |
| 3 | Seung Hyun Lee | 1 | Dong Nyoung Lee | 0 | 2 |
| 45 | Min Chul Kim | 1 | Dong Nyoung Lee | 0 | 2 |
| 23 | Sasha Hostyn | 1 | Dong Nyoung Lee | 2 | 4 |
| 52 | Juan Moreno Duran | 1 | Dong Nyoung Lee | 2 | 3 |
| 18 | Kang Dong Hyun | 1 | Dong Nyoung Lee | 2 | 1 |
| 22 | Jae Duck Lim | 1 | Dong Nyoung Lee | 1 | 2 |
| 108 | Jérémy Vansnick | 1 | Dong Nyoung Lee | 1 | 2 |
| 53 | Igor Turchin | 1 | Dong Nyoung Lee | 1 | 2 |
| 17 | Hyun Woo Park | 1 | Dong Nyoung Lee | 0 | 2 |
匹配表
+----------+------------+------------+---------+---------+--------+--------+---------+
| match_id | date | tournament | playerA | playerB | scoreA | scoreB | offline |
+----------+------------+------------+---------+---------+--------+--------+---------+
| 1 | 2012-12-04 | 799 | 4 | 55 | 1 | 3 | 0 |
| 2 | 2012-12-03 | 11921 | 2 | 41 | 2 | 0 | 0 |
| 3 | 2012-12-03 | 11921 | 21 | 41 | 0 | 2 | 0 |
| 4 | 2012-12-03 | 11921 | 3 | 2 | 2 | 1 | 0 |
| 5 | 2012-12-03 | 11921 | 41 | 2 | 1 | 2 | 0 |
| 6 | 2012-12-03 | 11921 | 21 | 3 | 1 | 2 | 0 |
| 7 | 2012-12-03 | 11924 | 1 | 8 | 2 | 1 | 1 |
| 8 | 2012-12-03 | 11924 | 1 | 8 | 2 | 3 | 1 |
| 9 | 2012-12-03 | 11924 | 8 | 19 | 3 | 2 | 1 |
| 10 | 2012-12-03 | 11924 | 19 | 12 | 2 | 1 | 1 |
+----------+------------+------------+---------+---------+--------+--------+---------+
+-----------+-----------+-----------------+-------------+------------+-----------+
| player_id | tag | real_name | nationality | birthday | game_race |
+-----------+-----------+-----------------+-------------+------------+-----------+
| 1 | Leenock | Dong Nyoung Lee | KR | 1995-04-01 | Z |
| 2 | Creator | Hyun Woo Jang | KR | 1996-08-19 | P |
| 3 | Life | Seung Hyun Lee | KR | 1997-01-11 | Z |
| 4 | DongRaeGu | Soo Ho Park | KR | 1991-06-03 | Z |
| 5 | PartinG | Lee Sak Won | KR | 1994-08-24 | P |
| 6 | TaeJa | Young Suh Yoon | KR | 1995-01-01 | T |
| 7 | Rain | Yoon Jong Jung | KR | 1992-08-14 | P |
| 8 | viOLet | Dong Hwan Kim | KR | 1990-12-05 | Z |
| 9 | Sniper | Tae Hoon Kwon | KR | 1995-01-22 | Z |
| 10 | Stephano | Ilyes Satouri | FR | 1993-03-12 | Z |
+-----------+-----------+-----------------+-------------+------------+-----------+
+--------+------+------------+------------+
| player | team | start_date | end_date |
+--------+------+------------+------------+
| 1 | 88 | 2011-02-23 | 2011-07-18 |
| 1 | 4 | 2011-07-18 | NULL |
| 2 | 3 | 2011-01-12 | NULL |
| 3 | 65 | 2010-10-19 | 2012-07-13 |
| 3 | 1 | 2012-07-13 | NULL |
| 4 | 7 | 2011-02-20 | NULL |
| 5 | 88 | 2010-10-29 | 2011-07-18 |
| 5 | 1 | 2012-10-21 | 2013-01-03 |
| 5 | 12 | 2013-01-14 | NULL |
| 6 | 65 | 2011-03-01 | 2011-05-01 |
+--------+------+------------+------------+
看起来查询正在生成一个半笛卡尔积
playermember开始日期结束日期球员一次只能是一支球队的成员
我们可能希望将匹配表中的日期
与成员表中的开始日期
和结束日期
进行比较。我们可能还想让它成为一个外部连接
LEFT
JOIN `member` mem2
ON mem2.player = m.playerB
AND mem2.start_date <= m.date
AND ( mem2.end_date > m.date OR mem2.end_date IS NULL )
左
加入'member'成员2
在mem2.player=m.playerB上
和mem2.start_date m.date或mem2.end_date为空）
请注意，其中一个日期比较包含一个相等值，而另一方则没有（因为对于相同的玩家，行上的开始日期似乎等于成员中另一行上的结束日期）
（对于日期为2011-07-18'
的比赛，哪个队是player=1
的成员？）
我们还希望处理end_date
中的NULL
值，在这种情况下，该值表示大于匹配的日期的大值
我们希望对<代码> MEM1使用相同的模式。
在你的匹配表的构造中存在一个初始问题。考虑下面的“翻转”每个玩家并将其分成一行。现在，随后的连接数立即减半：
select
piv, match_id, date, tournament, offline
, case when piv = 1 then playerA
else playerB
end as Player_id
, case when piv = 1 then scoreA
else scoreB
end as Score
from matches
cross join (select 1 as piv union all select 2) cj
matches表中的10行从该查询变为20行：
| piv | match_id | date | tournament | offline | Player_id | Score |
|-----|----------|----------------------|------------|---------|-----------|-------|
| 1 | 1 | 2012-12-04T00:00:00Z | 799 | 0 | 4 | 1 |
| 2 | 1 | 2012-12-04T00:00:00Z | 799 | 0 | 55 | 3 |
| 1 | 2 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 2 |
| 2 | 2 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 0 |
| 1 | 3 | 2012-12-03T00:00:00Z | 11921 | 0 | 21 | 0 |
| 2 | 3 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 2 |
| 1 | 4 | 2012-12-03T00:00:00Z | 11921 | 0 | 3 | 2 |
| 2 | 4 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 1 |
| 1 | 5 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 1 |
| 2 | 5 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 2 |
| 1 | 6 | 2012-12-03T00:00:00Z | 11921 | 0 | 21 | 1 |
| 2 | 6 | 2012-12-03T00:00:00Z | 11921 | 0 | 3 | 2 |
| 1 | 7 | 2012-12-03T00:00:00Z | 11924 | 1 | 1 | 2 |
| 2 | 7 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 1 |
| 1 | 8 | 2012-12-03T00:00:00Z | 11924 | 1 | 1 | 2 |
| 2 | 8 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 3 |
| 1 | 9 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 3 |
| 2 | 9 | 2012-12-03T00:00:00Z | 11924 | 1 | 19 | 2 |
| 1 | 10 | 2012-12-03T00:00:00Z | 11924 | 1 | 19 | 2 |
| 2 | 10 | 2012-12-03T00:00:00Z | 11924 | 1 | 12 | 1 |
因此，将其作为一个起点，加入球员数据非常简单，虽然对members表也很简单，但我们确实希望确保只从该表中获取他们的“当前”行，因此我们将今天的日期放在每个团队的开始/结束日期之间（如果结束日期为空，则使用今天的日期）
这不会进一步增加20行：
| piv | match_id | date | tournament | offline | Player_id | Score | player_id | tag | real_name | nationality | birthday | game_race | player | team | start_date | end_date |
|-----|----------|----------------------|------------|---------|-----------|-------|-----------|-----------|-----------------|-------------|----------------------|-----------|--------|--------|----------------------|----------|
| 1 | 7 | 2012-12-03T00:00:00Z | 11924 | 1 | 1 | 2 | 1 | Leenock | Dong Nyoung Lee | KR | 1995-04-01T00:00:00Z | Z | 1 | 4 | 2011-07-18T00:00:00Z | (null) |
| 1 | 8 | 2012-12-03T00:00:00Z | 11924 | 1 | 1 | 2 | 1 | Leenock | Dong Nyoung Lee | KR | 1995-04-01T00:00:00Z | Z | 1 | 4 | 2011-07-18T00:00:00Z | (null) |
| 1 | 2 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 2 | 2 | Creator | Hyun Woo Jang | KR | 1996-08-19T00:00:00Z | P | 2 | 3 | 2011-01-12T00:00:00Z | (null) |
| 2 | 4 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 1 | 2 | Creator | Hyun Woo Jang | KR | 1996-08-19T00:00:00Z | P | 2 | 3 | 2011-01-12T00:00:00Z | (null) |
| 2 | 5 | 2012-12-03T00:00:00Z | 11921 | 0 | 2 | 2 | 2 | Creator | Hyun Woo Jang | KR | 1996-08-19T00:00:00Z | P | 2 | 3 | 2011-01-12T00:00:00Z | (null) |
| 1 | 4 | 2012-12-03T00:00:00Z | 11921 | 0 | 3 | 2 | 3 | Life | Seung Hyun Lee | KR | 1997-01-11T00:00:00Z | Z | 3 | 1 | 2012-07-13T00:00:00Z | (null) |
| 2 | 6 | 2012-12-03T00:00:00Z | 11921 | 0 | 3 | 2 | 3 | Life | Seung Hyun Lee | KR | 1997-01-11T00:00:00Z | Z | 3 | 1 | 2012-07-13T00:00:00Z | (null) |
| 1 | 1 | 2012-12-04T00:00:00Z | 799 | 0 | 4 | 1 | 4 | DongRaeGu | Soo Ho Park | KR | 1991-06-03T00:00:00Z | Z | 4 | 7 | 2011-02-20T00:00:00Z | (null) |
| 2 | 7 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 1 | 8 | viOLet | Dong Hwan Kim | KR | 1990-12-05T00:00:00Z | Z | (null) | (null) | (null) | (null) |
| 2 | 8 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 3 | 8 | viOLet | Dong Hwan Kim | KR | 1990-12-05T00:00:00Z | Z | (null) | (null) | (null) | (null) |
| 1 | 9 | 2012-12-03T00:00:00Z | 11924 | 1 | 8 | 3 | 8 | viOLet | Dong Hwan Kim | KR | 1990-12-05T00:00:00Z | Z | (null) | (null) | (null) | (null) |
| 2 | 1 | 2012-12-04T00:00:00Z | 799 | 0 | 55 | 3 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 2 | 2 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 0 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 1 | 3 | 2012-12-03T00:00:00Z | 11921 | 0 | 21 | 0 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 2 | 3 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 2 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 1 | 5 | 2012-12-03T00:00:00Z | 11921 | 0 | 41 | 1 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 1 | 6 | 2012-12-03T00:00:00Z | 11921 | 0 | 21 | 1 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 2 | 9 | 2012-12-03T00:00:00Z | 11924 | 1 | 19 | 2 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 1 | 10 | 2012-12-03T00:00:00Z | 11924 | 1 | 19 | 2 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
| 2 | 10 | 2012-12-03T00:00:00Z | 11924 | 1 | 12 | 1 | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) | (null) |
注意：要恢复到信息的透视视图，请执行以下操作：
select
match_id, match_date, tournament
, max(case when piv = 1 then real_name end) PlayerAreal_name
, max(case when piv = 1 then player_Id end) PlayerA
, max(case when piv = 1 then player_Id end) ScoreA
, max(case when piv = 2 then real_name end) PlayerBreal_name
, max(case when piv = 2 then player_Id end) PlayerB
, max(case when piv = 2 then player_Id end) Scoreb
from (
the big query above goes here
)
group by
match_id, match_date, tournament
你能在这里写模式吗？不要显示多表查询的结果，而是显示每个表的一些数据。包括每个表的DDL也会有帮助。这就是你的意思吗？player|id | real|u name | player|id | real|u name | scoreA | scoreB | member1
对不起，我不知道你所说的模式是什么意思。只显示一个f每个表中的ew行（带标题）。这将对我们有所帮助。请将其包含在问题中（此处不作为注释，也不作为图片）不是多表中的行queries@Used_By_Already完成。如果您还需要什么，请告诉我。我如何更好地发现这些问题？我一天中的大部分时间都在关注这个问题，但无法解决它。我想我可以在设置连接后解决日期问题。当我构建这样的查询时，我会将主或唯一的k选择列表开头的每个表的Y列，并按相同的主键列排序。避免重复的关键是确定关系的保证基数…我需要知道它是否保证为一对一，或一对零或一，或一对零或多，或多对多。您能帮帮忙吗我明白吗？我不明白piv是什么，它来自哪里，以及它是如何产生的。我想记录从47k翻倍到92k的原因是你把每个玩家放在自己的线上，对吗？交叉连接是如何工作的？我从来没有使用过它们。交叉连接的缩写是cj
（选择1作为piv union all select 2）cj
？交叉连接将行无条件地放在一起（实际上它是行的倍数）。是cj=CROSS JOIN=YES。“piv”只是我从稀薄的空气中提取的一个列名，是piv piv union all select 2的缩写。它是由选择1作为piv union all select 2“生成”的，尝试一下，它只输出2行。“记录从47k翻倍到92k的原因是你把每个球员都放在了自己的线上，对吗？”=是的
select
match_id, match_date, tournament
, max(case when piv = 1 then real_name end) PlayerAreal_name
, max(case when piv = 1 then player_Id end) PlayerA
, max(case when piv = 1 then player_Id end) ScoreA
, max(case when piv = 2 then real_name end) PlayerBreal_name
, max(case when piv = 2 then player_Id end) PlayerB
, max(case when piv = 2 then player_Id end) Scoreb
from (
the big query above goes here
)
group by
match_id, match_date, tournament
| match_id | match_date | tournament | PlayerAreal_name | PlayerA | ScoreA | PlayerBreal_name | PlayerB | Scoreb |
|----------|----------------------|------------|------------------|---------|--------|------------------|---------|--------|
| 1 | 2012-12-04T00:00:00Z | 799 | Soo Ho Park | 4 | 4 | (null) | 55 | 55 |
| 2 | 2012-12-03T00:00:00Z | 11921 | Hyun Woo Jang | 2 | 2 | (null) | 41 | 41 |
| 3 | 2012-12-03T00:00:00Z | 11921 | (null) | 21 | 21 | (null) | 41 | 41 |
| 4 | 2012-12-03T00:00:00Z | 11921 | Seung Hyun Lee | 3 | 3 | Hyun Woo Jang | 2 | 2 |
| 5 | 2012-12-03T00:00:00Z | 11921 | (null) | 41 | 41 | Hyun Woo Jang | 2 | 2 |
| 6 | 2012-12-03T00:00:00Z | 11921 | (null) | 21 | 21 | Seung Hyun Lee | 3 | 3 |
| 7 | 2012-12-03T00:00:00Z | 11924 | Dong Nyoung Lee | 1 | 1 | Dong Hwan Kim | 8 | 8 |
| 8 | 2012-12-03T00:00:00Z | 11924 | Dong Nyoung Lee | 1 | 1 | Dong Hwan Kim | 8 | 8 |
| 9 | 2012-12-03T00:00:00Z | 11924 | Dong Hwan Kim | 8 | 8 | (null) | 19 | 19 |
| 10 | 2012-12-03T00:00:00Z | 11924 | (null) | 19 | 19 | (null) | 12 | 12 |