Question

我正在尝试将来自两组不同表的结果合并为一个结果。这是我到目前为止的查询：

SELECT * 
FROM ( SELECT product_table1.product_id as product_id, sum(product_table1.qty) as quantity, sum(product_table1.paid) as amount  
FROM product_table1
LEFT JOIN table2 ON table2.id = product_table1.table2_id
WHERE product_table1.product_id IN ( SELECT id FROM products_table WHERE active = 'yes' )
AND table2.active = 'yes'
GROUP BY product_id

UNION 

SELECT product_table2.product_id as product_id, sum(product_table2.qty) as quantity, sum(product_table2.paid) as amount 
FROM product_table2
LEFT JOIN table3 ON table3.id = product_table2.table3_id
WHERE product_table2.product_id IN ( SELECT id FROM products_table WHERE active = 'yes' )
AND table3.active = 'yes'
GROUP BY product_id

) AS product_sales

以下是数据的回传方式：

product_id | quantity | amount
1            100        200
2            200        300
3            300        600
1            500        700
4            200        200

我试图弄清楚如何最好地采用这两组数字（每组具有相同数量的列和数据类型），并将它们组合成一组结果，而不必将php带入其中。这可能吗？

我找到了其他一些解决方案，但我不确定它们是否符合我的要求。我认为Example of another solution是我需要的，但不确定......

Answer 1

在外部GROUP BY和SELECT代替UNION ALL

使用UNION

SELECT product_id,  
       SUM(quantity) as quantity,
       SUM(amount) as amount
  FROM ( 
    SELECT product_table1.product_id as product_id, 
           SUM(product_table1.qty) as quantity, 
           SUM(product_table1.paid) as amount  
      FROM product_table1
      LEFT JOIN table2 ON table2.id = product_table1.table2_id
     WHERE product_table1.product_id IN ( SELECT id FROM products_table WHERE active = 'yes' )
       AND table2.active = 'yes'
     GROUP BY product_id
     UNION ALL
    SELECT product_table2.product_id as product_id, 
           SUM(product_table2.qty) as quantity, 
           SUM(product_table2.paid) as amount 
      FROM product_table2
      LEFT JOIN table3 ON table3.id = product_table2.table3_id
     WHERE product_table2.product_id IN ( SELECT id FROM products_table WHERE active = 'yes' )
       AND table3.active = 'yes'
     GROUP BY product_idc) AS product_sales
 GROUP BY product_id

Answer 2

只需进行汇总：

select product_id, sum(quantity) as quantity, sum(amount) as amount
from (<your query here>)
group by product_id

我想补充一点，您可能希望使用union all代替union。如果两个源返回完全相同的值，您可能希望保留两者（union删除重复项。）

MYSQL联合并组合重复行的金额

2 个答案: