Question

如何转换此结果：

Group     |  Sum
Services  | 11120.99
Vendas    | 3738.00

分为：

Group     |  Sum
Services  | 74.84
Vendas    | 25.16

也就是说，第二个显示结果为总数的百分比。

这就是我的尝试：

SELECT categories.cat AS 'Group', SUM(atual) AS 'Sum'
FROM `table1` INNER JOIN
     categories
     ON table1.category_id=categories.id
GROUP BY categoria

Answer 1

你可以离开加入未分组或拆分的总和，并将其除以总和查询。通过这种方式，您只需执行一次总选择以获得更快的运行时间

SELECT cat, sum_atual, sum_atual/total_atual as percent_atual 
FROM
(   SELECT categories.cat AS cat, SUM(atual) AS sum_atual
    FROM `table1` 
    JOIN categories ON table1.category_id=categories.id
    GROUP BY categoria
) t
LEFT JOIN 
(   SELECT SUM(atual) as total_atual
    FROM `table1`
) t1

Answer 2

SELECT categories.cat AS categoria, 
       SUM(atual) * 100 / (select sum(atual) from table1) AS percentages 
FROM `table1` 
INNER JOIN categories ON table1.category_id=categories.id 
GROUP BY categoria

Answer 3

你可以通过以下几种方式做到这一点。一种是在select子句中使用子查询。如下所示，这假设category_id中的table1列始终与categories匹配：

SELECT c.categoria AS "Group", SUM(t1.atual) AS "Sum",
       SUM(t1.atual) / (SELECT SUM(t1.atual) FROM table1) as "Percent"
FROM `table1` t1 INNER JOIN
     categories c
     ON t1.category_id = c.id
GROUP BY c.categoria;

我也改变了group by条款。 group by和select使用相同的列是个好主意。我在所有列引用中添加了表别名，这是另一种好的做法。

MySQL查询计算总列的百分比

3 个答案: