MySQL query data by hour, fill in 0 if there is no data

CREATE TABLE hours_list (
 hour int NOT NULL PRIMARY KEY
)

	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