mysql按月查询统计（统计近12个月的项目个数）

mysql按月查询统计，没有数据的填充为0

1.获取过去12个月所有的月份

SELECT DATE_FORMAT((CURDATE() - INTERVAL 1 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 2 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 3 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 4 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 5 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 6 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 7 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 8 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 9 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 10 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 11 MONTH), '%Y-%m') AS `month`
UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 12 MONTH), '%Y-%m') AS `month`

运行结果：

2.把上面的月份与显示数据进行关联查询

-- 统计近12个月的项目个数（project 表没有的月份补齐）
select d.`month`,count(p.id) as `count`
from(
  SELECT DATE_FORMAT((CURDATE() - INTERVAL 1 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 2 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 3 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 4 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 5 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 6 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 7 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 8 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 9 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 10 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 11 MONTH), '%Y-%m') AS `month`
	UNION SELECT DATE_FORMAT((CURDATE() - INTERVAL 12 MONTH), '%Y-%m') AS `month`
	)d
	left join project p on DATE_FORMAT(p.plan_start_date, '%Y-%m')=d.`month`
	group by month

运行结果：