MySQL UNION ALL 与 LEFT JOIN 返回双精度值

Question

我有多个表试图在 MySql 中使用 UNION ALL 和 LEFT JOIN 从所有表中获取值，我使用的查询如下所示。

(SELECT 
   t1.name, t2.cat, t3.utt, t4.gcost, t4.net
 FROM table_one as t1
   LEFT JOIN table_three as t2
     ON t2.id = t1.ct
   LEFT JOIN table_four as t3
     ON t3.id = t1.ut
   LEFT JOIN table_five as t4
     ON t4.gid = t1.id
 ) UNION ALL
 (SELECT 
   t1.name, t2.cat, t3.utt, t4.gcost, t4.net
 FROM table_tow as t1
   LEFT JOIN table_three as t2
     ON t2.id = t1.ct
   LEFT JOIN table_four as t3
     ON t3.id = t1.ut
   LEFT JOIN table_five as t4
     ON t4.gid = t1.id
 )

但是上面的查询 return double values in MySQL

这里是 fiddle link: http://sqlfiddle.com/#!9/bd30ba/1

如有任何帮助，我们将不胜感激。

谢谢

更新

根据 P.Salmon 问题了解上述查询用于固定资产应用程序的完整逻辑，因此固定资产具有多个项目值，例如：

实际价格。
累计折旧
当前值
...

所以 fiddle 中的查询有 2 个不同的 price/amount 查询应该 return 每个引用行 ID 的两个值。

Answer 1

您只想要一个并且真的不在乎哪个然后最大化 t5 详细信息

select t1.name,t3.cat,t4.utt, 
         t5.gcost,t5.net
 from
 (
 select * from table_one
 union all
 select * from table_two) t1
 LEFT JOIN table_three as t3 ON t3.id = t1.ct
 LEFT JOIN table_four as t4            ON t4.id = t1.ct
 left join (select gid,max(gcost) gcost,max(net) net from table_five group by gid) t5 on t5.gid = t1.id;
+--------------+------+------+-------+------+
| name         | cat  | utt  | gcost | net  |
+--------------+------+------+-------+------+
| Green Apple  | A    | AAA  |  3000 | 6542 |
| Small Orange | B    | BBB  |  2560 | 6542 |
| Small Banana | C    | CCC  |  5800 | 6542 |
| Small Mango  | C    | DDD  |  2560 | 6542 |
| Red Apple    | A    | AAA  |  3000 | 6542 |
| Big Orange   | B    | BBB  |  2560 | 6542 |
| Big Banana   | C    | CCC  |  5800 | 6542 |
| Big Mango    | C    | DDD  |  2560 | 6542 |
+--------------+------+------+-------+------+
8 rows in set (0.072 sec)

Answer 2

谢谢大家的帮助，但其中 none 帮助了我，我知道 table_five 中有重复的 ID，来自 table_one 和 table_tow...我解决问题的唯一方法是在 table_one、table_tow ... AS

中添加新的序列 ID

seq_.time();

相同的序列在插入过程中添加 table_five.. 之后我将查询更改为.

(SELECT 
   t1.name, t2.cat, t3.utt, t4.gcost, t4.net
 FROM table_one as t1
   LEFT JOIN table_three as t2
     ON t2.id = t1.ct
   LEFT JOIN table_four as t3
     ON t3.id = t1.ut
   LEFT JOIN table_five as t4
     ON t4.gid = t1.id
     AND t4.seq = t1.seq
 ) UNION ALL
 (SELECT 
   t1.name, t2.cat, t3.utt, t4.gcost, t4.net
 FROM table_tow as t1
   LEFT JOIN table_three as t2
     ON t2.id = t1.ct
   LEFT JOIN table_four as t3
     ON t3.id = t1.ut
   LEFT JOIN table_five as t4
     ON t4.gid = t1.id
    AND t4.seq = t1.seq
 )

现在我得到了我想要的准确数据。谢谢

MySQL UNION ALL 与 LEFT JOIN 返回双精度值

MySQL UNION ALL with LEFT JOIN returning double values

mysql

innodb