如何使用mysql减少嵌套查询时间

Question

如何使用任何类型的连接或子查询或嵌套查询减少此查询运行时间。

select 
`p`.`id`,
`p`.`name`,
SUM(s.quantity) as inst,
from `product` as `p` 
LEFT JOIN  sales as s ON s.pid=p.`id` AND s.sales_id IN (SELECT invoice.invoice_id FROM invoice WHERE invoice.ccid NOT IN (SELECT ccid FROM ticket WHERE st='1'))
where `p`.`hc` = '1' 
GROUP BY `p`.`id` 
order by `p`.`name` DESC 

Answer 1

在故障单的st上添加索引，并在发票的ccid和sales的sales_id上添加索引。

在查询之前尝试使用Explain子句是否在possible_keys列输出中使用了创建的索引。

Answer 2

最后我来找一个解决方案＆amp;它有效

select 
s.pid,
SUM(s.quantity) AS squan 
from invoice as i 
LEFT JOIN sales as s ON s.sales_id=i.invoice_id
LEFT JOIN crt ON crt.cc_id=i.cc_id AND crt.ch='0'
WHERE 
crt.ch='0' 
AND 
(i.cc_id!='' OR i.cc_id!='0') 
GROUP BY i.invoice_id