我有一个问题，我正在努力加快速度。我确信有一种方法可以提高效率，但我缺乏知识。
订单 - 这显示每个订单收到一行（目前为800,000行）
orders_financials - 显示与订单相关的每笔金融交易一行（目前为2,000,000行）
orders_financials表每个订单包含多行，交易类别显示在financialType
中因此，例如，对于一个订单，orders_financials中可能有5行
financialType = 14: value = 10.00
financialType = 12: value = 7.00
financialType = 18: value = 2.50
financialType = 15: value = 0.30
financialType = 17: value = 7.50
对于每个订单，将有不同数量的数据。随着时间的推移，会向系统添加更多数据，并将新行添加到orders_financials。
我要做的是运行一个查询，允许我为每个订单获取一行，并为此行计算几类金融交易的总计。
下面的查询应该给我所有由customerID 279发出的订单：
select
orders.orderID,
customers.username,
(select group_concat(financialRef) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (17) ) ref,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (17) ) costs_cost,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (12,13) ) costs_exp,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (14) ) costs_sell,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (15) ) costs_sell_out,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (1,2,3,9,11) ) extras_in,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (4,5) ) extras_out,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (20) ) extras_back,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (18) ) insurance_in,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (10,6) ) insurance_out,
(select sum(amount) from orders_financials where orders_financials.orderID=orders.orderID and financialType IN (19) ) insurance_back
from orders
left join customers on orders.customerID=customers.customerID
where customers.customerID='279'
order by orderID
（仅供参考，订单表中有18,263条记录，其中customerID = 279）
您会看到财务类型的12或13可以合计以得出costs_exp。同样1,2 3,9,11都是extras_in。
最终结果是包含大量数据的精彩查询，但它提供了每个订单的详细概述。在where子句中，我可以按客户，服务，日期范围等进行搜索
我的问题是此查询需要年龄才能运行。我必须以非常低效的方式进行，因为查询的每个元素都是快速的。
从慢速日志中我可以看到它正在迭代422,000,000行
Query_time: 528.107584 Lock_time: 0.000652 Rows_sent: 1388 Rows_examined: 422442417
必须有一种更有效的方式，但我很难看到。
编辑 - 以下是上述查询的解释：
+----+--------------------+-------------------+-------+-----------------------+---------------+---------+---------------------------+--------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+-------------------+-------+-----------------------+---------------+---------+---------------------------+--------+--------------------------+
| 1 | PRIMARY | customers | const | PRIMARY | PRIMARY | 4 | const | 1 | |
| 1 | PRIMARY | orders | ref | customerID | customerID | 5 | const | 24802 | Using where; Using index |
| 12 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 1 | Using where |
| 11 | DEPENDENT SUBQUERY | orders_financials | range | orderID,financialType | financialType | 4 | NULL | 2 | Using where |
| 10 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 49717 | Using where |
| 9 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 1 | Using where |
| 8 | DEPENDENT SUBQUERY | orders_financials | range | orderID,financialType | financialType | 4 | NULL | 2 | Using where |
| 7 | DEPENDENT SUBQUERY | orders_financials | range | orderID,financialType | financialType | 4 | NULL | 5 | Using where |
| 6 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 139 | Using where |
| 5 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | orderID | 4 | p4db_admin.orders.orderID | 236338 | Using where |
| 4 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | orderID | 4 | p4db_admin.orders.orderID | 236338 | Using where |
| 3 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 99966 | Using where |
| 2 | DEPENDENT SUBQUERY | orders_financials | ref | orderID,financialType | financialType | 4 | const | 99966 | Using where |
+----+--------------------+-------------------+-------+-----------------------+---------------+---------+---------------------------+--------+--------------------------+
13 rows in set (0.00 sec)
答案 0 :(得分：4)
SELECT a.orderID,
b.username,
GROUP_CONCAT(CASE WHEN c.financialType = 17 THEN c.financialRef END) ref,
SUM(CASE WHEN c.financialType IN (12,13) THEN c.amount END) costs_cost,
SUM(CASE WHEN c.financialType = 14 THEN c.amount END) costs_exp,
SUM(CASE WHEN c.financialType = 15 THEN c.amount END) costs_sell,
SUM(CASE WHEN c.financialType IN (1,2,3,9,11) THEN c.amount END) extras_in,
SUM(CASE WHEN c.financialType IN (4,5) THEN c.amount END) extras_out,
SUM(CASE WHEN c.financialType = 20 THEN c.amount END) extras_back,
SUM(CASE WHEN c.financialType = 18 THEN c.amount END) insurance_in,
SUM(CASE WHEN c.financialType IN (10,6) THEN c.amount END) insurance_out,
SUM(CASE WHEN c.financialType = 19 THEN c.amount END) insurance_back
FROM orders a
LEFT JOIN customers b
ON a.customerID = b.customerID
LEFT JOIN orders_financials c
ON a.orderID = c.orderID
GROUP BY a.orderID, b.username
在orders_financials.financialType
ALTER TABLE orders_financials ADD INDEX (financialType)