mysql按月統計時,某月沒有數據 將此月補充並值爲0mysql
解決:建立一個月分表進行左鏈接sql
如圖是月份表spa
查詢時select
SELECT a.i months,IFNULL(b.count,0) count from 月份表 a LEFT JOIN (
select DATE_FORMAT(cjsj,'%m') months,count(*) count from 被查表 where year(cjsj)='2017' group by monthsim
) b on a.i = b.months ORDER BY a.i統計