本篇文章小编给大家分享一下MySQL按小时查询数据没有的补0代码示例,文章代码介绍的很详细,小编觉得挺不错的,现在分享给大家供大家参考,有需要的小伙伴们可以来看看。
需求背景
一个统计接口,前端需要返回两个数组,一个是0-23的小时计数,一个是各小时对应的统计数。
思路 直接使用group by查询要统计的表,当某个小时统计数为0时,会没有该小时分组。思考了一下,需要建立辅助表,只有一列小时,再插入0-23共24个小时
CREATE TABLE hours_list ( hour int NOT NULL PRIMARY KEY )
先查小时表,再做连接需要查的表,即可将没有统计数的小时填充上0。这里由于需要查多个表中,create_time在每个小时区间内、且SOURCE_ID等于查询条件的统计之和,所以UNION ALL了多张表
SELECT t.HOUR, sum(t.HOUR_COUNT) hourCount FROM (SELECT hs. HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_0002 cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR UNION ALL SELECT hs.HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_hs cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR UNION ALL SELECT hs.HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_kfyj cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR UNION ALL SELECT hs.HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_his_0002 cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR UNION ALL SELECT hs.HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_his_hs cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR UNION ALL SELECT hs.HOUR AS HOUR, COUNT(cs.RECORD_ID) AS HOUR_COUNT FROM cbc_hours_list hs LEFT JOIN cbc_source_his_kfyj cs ON HOUR (cs.create_time) = hs. HOUR AND cs.create_time > #{startTime} AND cs.create_time <= #{endTime} <#if sourceId?exists && sourceId !=''> AND SOURCE_ID = #{sourceId} #if> GROUP BY hs. HOUR) t GROUP BY t.hour
效果
统计数为0的小时也可以查出来了。