Question

我想减少SQL请求的处理时间（实际上它运行10分钟......）我认为问题来自嵌套的SQL查询。（对不起我的英语，我是法国学生）

SELECT DISTINCT `gst.codeAP21`, `gst.email`, `gst.date`, `go.amount` 
FROM globe_statistique 
JOIN globe_customers ON `gst.codeAP21`=`gc.codeAP21` 
JOIN globe_orders ON `gc.ID`=`go.FK_ID_customers` 
WHERE `gst.page` = 'send_order' 
AND `gst.date` = FROM_UNIXTIME(`go.date`,'%%Y-%%m-%%d') 

UNION 

SELECT DISTINCT `gst.codeAP21`, `gst.email`, `gst.date`, '-' 
FROM globe_statistique 
WHERE `gst.page` NOT LIKE 'send_order' "
AND (`gst.codeAP21`,`gst.date`) NOT IN 
            ( SELECT `gst.codeAP21`,`gst.date` FROM globe_statistique 
              WHERE `gst.page`='send_order');

由于

Answer 1

试试这个：

SELECT DISTINCT `gst.codeAP21`, `gst.email`, `gst.date`, `go.amount` 
FROM globe_statistique 
JOIN globe_customers ON `gst.codeAP21`=`gc.codeAP21` 
JOIN globe_orders ON `gc.ID`=`go.FK_ID_customers` 
WHERE `gst.page` = 'send_order' 
AND `gst.date` = FROM_UNIXTIME(`go.date`,'%%Y-%%m-%%d') 

UNION 
SELECT DISTINCT t1.`gst.codeAP21`, t1.`gst.email`, t1.`gst.date`, '-' 
FROM globe_statistique t1 
left join globe_statistique t2 on t1.gst.page =t2.gst.page and t1.gst.date =t2.gst.date and t2.gst.page =send_order
WHERE `gst.page` <> 'send_order' AND t2.gst.date is null

但我建议重命名你的列名并删除这些点。

还可以使用EXPLAIN找出查询速度慢的原因并添加正确的索引

Answer 2

尽量避免使用不同的。为此，应使用UNION ALL。最后的分组给出了相同的结果：

select codeAP21, email, date, amount 
from ( --> your query without distinct but with UNION ALL <-- ) 
group by codeAP21, email, date, amount

请参阅：Huge performance difference when using group by vs distinct

sql请求太长了......如何简化？

2 个答案: