MySQL查询：多个日期范围的客户订单值和订单计数

Question

我有以下查询，该查询对于在定义的时间段内返回每位客户的订单数和价值非常有用。

SELECT 
c.company, 
c.email, 
SUM(o.total_value) AS ttl_order_value, 
COUNT(p.order_id) AS ttl_order_count 
FROM merch_orders_ist AS o 
    INNER JOIN contacts_ern AS c 
    ON (o.contact_id = c.contactid) 
    INNER JOIN merch_payments_ist AS p 
    ON (o.id = p.order_id) 
WHERE DATE(p.date_of_payment) BETWEEN '2014-01-01' AND '2014-12-31' 
GROUP BY c.contactid 
ORDER BY ttl_order_value DESC 

我需要扩展该查询添加两个更多的列，其包括顺序总数和用于第二日期范围（例如2015和2014）每客户的订单的求和值。我期待的结果看起来像这样...

| company | email | ttl_order_value_2015 | ttl_order_count_2015 | ttl_order_value_2014 | ttl_order_count_2014 | 
--------------------------------------------------------------------------------------------------------------- 

在此先感谢您！

Answer 1

我已经给出了需要修改但是应该根据您的要求工作的伪代码。

注意：如果语法不起作用，则将SUM（o.total_value）移除到o.total_value。你可以使用SUM通过编写一个简单的外部查询和分组

SELECT 
c.company, 
c.email, 
-- Using date put some condtions like >,< or extarct year and compare 
DECODE(p.date_of_payment, '2014',SUM(o.total_value),0) AS ttl_order_value_2014, 
Decode(p.date_of_payment,'2014' ,COUNT(p.order_id),0) AS ttl_order_count_2014, 

DECODE(p.date_of_payment, '2015',SUM(o.total_value),0) AS ttl_order_value_2015, 
Decode(p.date_of_payment,'2015' ,COUNT(p.order_id),0) AS ttl_order_count_2015, 

FROM merch_orders_ist AS o 
    INNER JOIN contacts_ern AS c 
    ON (o.contact_id = c.contactid) 
    INNER JOIN merch_payments_ist AS p 
    ON (o.id = p.order_id) 
WHERE DATE(p.date_of_payment) BETWEEN '2014-01-01' AND '2014-12-31' 
GROUP BY c.contactid 
ORDER BY ttl_order_value DESC