Question

我有3个MySQL表来检索它们的数据。

table1包含行：

id | name       | total_amount | product_id | date
---------------------------------------------
1  | some name  | some amount  | some pid   | some date
2  | some name1 | some amount1 | some pid1  | some date1
3  | some name2 | some amount2 | some pid2  | some date2
4  | some name3 | some amount3 | some pid3  | some date3

和table2：

product_id | product_name
-------------------
some pid   | some product name
some pid1  | some product name1
some pid2  | some product name2
some pid3  | some product name3

和table3：

id | total_amount  | product_id
-------------------------------
1  | some amount   | some pid 
2  | some amount2  | some pid2

我正在使用table1和table2之间的内部联接及其product_id列出如下值：

name       | total_amount | product_id | product_name        | date
--------------------------------------------------
some name  | some amount  | some pid   | some product name   | some date
some name1 | some amount1 | some pid1  | some product name1  | some date1
some name2 | some amount2 | some pid2  | some product name2  | some date2
some name3 | some amount3 | some pid3  | some product name3  | some date3

但是，如果table3的total_amount和product_id与table1的total_amount和product_id具有相同的值，我不想在连接表列表中显示行。

所以我希望我的输出像：

name       | total_amount | product_id | product_name        | date
--------------------------------------------------
some name1 | some amount1 | some pid1  | some product name1  | some date1
some name3 | some amount3 | some pid3  | some product name3  | some date3

是否可以使用SQL Query执行此操作，还是应该尝试使用客户端语言PHP？

Answer 1

Yu可以使用以下查询：

SELECT t1.*, t2.*
FROM table1 AS t1
JOIN table2 AS t2 ON t1.product_id = t2.product_id 
LEFT JOIN table3 AS t3 ON t3.product_id = t2.product_id AND t1.total_amount = t3.total_amount
WHERE t3.product_id IS NULL

以上查询在字段table1上加入table2和product_id，并在table3中具有相同product_id的匹配记录时筛选出记录和total_amount值。

Answer 2

直截了当的方法是使用NOT EXISTS或NOT IN：

select t1.name, t1.total_amount, t1.product_id, t2.product_name, t1.date
from t1
join t2 on t2.product_id = t1.product_id
where (t1.total_amount, t1.product_id) not in
(
  select t3.total_amount, t3.product_id
  from t3
);

组合3个不同的MySQL表的值，连接表1和表2，并检查此连接中是否存在表3值

2 个答案: