我希望得到一个项目#QTYs的SUM分组为几个月,查询需要太长时间(15 – 20)秒才能获取.

– 总行数：1495873

-Total Fetched rows：9 – 12

两个表(invoice_header和invoice_detail)之间的关系是(一对多),invoice_header是发票的标题,只有总计.使用位置ID(loc_id)和发票编号(invo_no)链接到invoice_detail,因为每个位置都有自己的序列号.发票明细包含每张发票的详细信息.

有没有更好的方法来增强该查询的性能,这里是：

SELECT SUM(invoice_detail.qty) AS qty, Month(invoice_header.date) AS month

FROM invoice_detail

JOIN invoice_header ON invoice_detail.invo_no = invoice_header.invo_no

AND invoice_detail.loc_id = invoice_header.loc_id

WHERE invoice_detail.item_id = {$itemId}

GROUP BY Month(invoice_header.date)

ORDER BY Month(invoice_header.date)

说明：

invoice_header表结构：

CREATE TABLE `invoice_header` (

`invo_type` varchar(1) NOT NULL,

`invo_no` int(20) NOT NULL AUTO_INCREMENT,

`invo_code` varchar(50) NOT NULL,

`date` date NOT NULL,

`time` time NOT NULL,

`cust_id` int(11) NOT NULL,

`loc_id` int(3) NOT NULL,

`cash_man_id` int(11) NOT NULL,

`sales_man_id` int(11) NOT NULL,

`ref_invo_no` int(20) NOT NULL,

`total_amount` decimal(19,2) NOT NULL,

`tax` decimal(19,2) NOT NULL,

`discount_amount` decimal(19,2) NOT NULL,

`net_value` decimal(19,2) NOT NULL,

`split` decimal(19,2) NOT NULL,

`qty` int(11) NOT NULL,

`payment_type_id` varchar(20) NOT NULL,

`comments` varchar(255) NOT NULL,

PRIMARY KEY (`invo_no`,`loc_id`)

) ENGINE=InnoDB AUTO_INCREMENT=20286 DEFAULT CHARSET=utf8

invoice_detail表结构：

CREATE TABLE `invoice_detail` (

`invo_no` int(11) NOT NULL,

`loc_id` int(3) NOT NULL,

`serial` int(11) NOT NULL,

`item_id` varchar(11) NOT NULL,

`size_id` int(5) NOT NULL,

`qty` int(11) NOT NULL,

`rtp` decimal(19,2) NOT NULL,

`type` tinyint(1) NOT NULL,

PRIMARY KEY (`invo_no`,`loc_id`,`serial`),

KEY `item_id` (`item_id`),

KEY `size_id` (`size_id`),

KEY `invo_no` (`invo_no`),

KEY `serial` (`serial`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8

解决方法:

遵循SQL需要多长时间？

SELECT count(*)

FROM invoice_detail

WHERE invoice_detail.item_id = {$itemId}

如果此SQL需要15-20秒,则应在inovice_detail表的字段item_id上添加索引.

invoice_header已在invo_no和loc_id的连接列上拥有主键,因此您无需在invoice_header表上添加其他索引.但是如果你在字段invo_no,loc_id和date上添加一个索引,那么只能通过索引扫描来增强一点性能.

标签：mysql,sql,sql-execution-plan,performance

来源： https://codeday.me/bug/20190703/1362962.html