Question

mysql 执行后 sending data 占用时间82% 的时间 总耗时要3秒左右，关键是我是在NetBeans中关联这个视图

不可能每次执行程序都要等3秒。

SELECT
`pd`.`id` AS `id`,
`pd`.`Service_number` AS `Service_number`,
`pd`.`project_date` AS `project_date`,
`pd`.`project_name` AS `project_name`,
`pd`.`Responsible_project` AS `Responsible_project`,
`pd`.`Business_units` AS `Business_units`
FROM
`project_detail` `pd`
WHERE
NOT
EXISTS（
SELECT
1
FROM
`project_detail`
WHERE
`project_detail`.`Service_number` = `pd`.`Service_number`
AND
`project_detail`.`project_date` > `pd`.`project_date`）

Answer 1

explain看一下,然后尽量不要用子查询,把你的场景说一下,看看哪块可以优化一下

追问

我也不太想用子查询，可是这个好像比较需要。要根据project_date最大来去除号码重复。而且我还有几个这样的视图，他们运行都比较快，就这个执行要3秒左右！