mysql分类统计数量

1:SELECT SUM(总藏书量),SUM(管内剩余) FROM `藏书信息` GROUP BY 入库时间

2:SELECT SUM(总藏书量)/count(总藏书量),SUM(管内剩余)/count(管内剩余) FROM `藏书信息` GROUP BY 入库时间

select DATE_FORMAT(来电时间,'%Y-%m') as 月, 问题类别 , count(1) as 数量 from

( select 来电时间, 问题类别 from mytable where 问题类别 = '农村用水投诉' ) tmptable

group by DATE_FORMAT(来电时间,'%Y-%m') ,问题类别 ORDER BY 月 ASC

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