Question

如何合并以下多个选择查询的结果，以便可以在一个合并的视图中获得有关所有战斗的信息。要获得完整的架构，请查看here，因为stackoverflow限制了我可以编写多少代码来描述问题。

|battle.id  |Attackers       | Defender           | Winner         |
--------------------------------------------------------------------
|    1      |'rishabhchauhan'|'vaibhavchauhan'    |'vaibhavchauhan'|
|    2      |'abhishekgaur'  |'vaibhavchauhan'    |'vaibhavchauhan'|
|    3      |'AnkitSharma'   |'vaibhavchauhan'    |'vaibhavchauhan'|
....

查询以查找攻击者姓名：

select CONCAT(player.firstname, player.lastname) as Attacker, Battles.battle_id 
from ((player inner 
join Attacker_Battles on Attacker_Battles.player_id = player.player_id ) 
inner join Battles on Battles.battle_id = Attacker_Battles.battle_id);

查询以找到防御者姓名：

select CONCAT(player.firstname, player.lastname) as Defenders, Battles.battle_id 
from ((player inner 
join Defender_Battles on Defender_Battles.player_id = player.player_id ) 
inner join Battles on Battles.battle_id = Defender_Battles.battle_id);

查询以查找获奖者姓名：

select CONCAT(player.firstname, player.lastname) as Winners, Battles.battle_id 
from ((player inner 
join Winner_battles on Winner_battles.player_id = player.player_id ) 
inner join Battles on Battles.battle_id = Winner_battles.battle_id);

Answer 1

要将所有查询合并为一个查询，您只需要将JOIN表Battles到每个Attacker_Battles等表中，然后将每个查询都{{1 }}表以获取适当的名称。这样的事情应该起作用：

player

输出（用于您的pastebin数据）

SELECT CONCAT(pa.firstname, pa.lastname) AS Attacker,
       CONCAT(pd.firstname, pd.lastname) AS Defender,
       CONCAT(pw.firstname, pw.lastname) AS Winner,
       b.battle_id As Battle
FROM Battles b
JOIN Attacker_Battles ab ON ab.battle_id = b.battle_id
JOIN player pa ON pa.player_id = ab.player_id
JOIN Defender_Battles db ON db.battle_id = b.battle_id
JOIN player pd ON pd.player_id = db.player_id
JOIN Winner_Battles wb ON wb.battle_id = b.battle_id
JOIN player pw ON pw.player_id = wb.player_id

Demo on SQLFiddle

查询也可以如下编写（也许更直观）。如果给定的Attacker Defender Winner Battle rishabhchauhan vaibhavchauhan vaibhavchauhan 1 abhishekgaur pawanyadav abhishekgaur 2 abhishekgaur pawanyadav abhishekgaur 3 AnkitSharma JayantVerma AnkitSharma 4 vaibhavchauhan JayantVerma JayantVerma 5 rishabhchauhan abhishekgaur rishabhchauhan 6 vaibhavchauhan AnkitSharma vaibhavchauhan 8可能没有Battle，Attacker和Defender，则此查询中的顶级Winner可以替换为JOIN：

LEFT JOIN

Demo on SQLFiddle

在不使用笛卡尔联接的情况下将许多sql查询上的结果合并

1 个答案: