MySQL按小时查询数据,没有的补0
时间：2022-03-25 09:40:54 | 栏目：Mysql | 点击：次
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。
