这个数据集里的空冷前降温数据查不到，是哪里不对吗

select a.*,b.空冷后温降 from

(select a.stat_date,a.炉盖温度平均值 - b.空冷前温度平均值 as 空冷前温降 from

(select stat_date,CONVERT(average_value,DECIMAL(12,2)) as 炉盖温度平均值 from mom_process_index_daily_statistic where pt_number in("KD_JH15#16#_15#_KLQWD") 

AND DATE_FORMAT(stat_date,'%Y-%m-%d') >= '${DATEINMONTH(TODAY(),1)}' AND DATE_FORMAT(stat_date,'%Y-%m-%d') <='${today()}')a

left join

(select stat_date,CONVERT(average_value,DECIMAL(12,2)) as 空冷前温度平均值 from mom_process_index_daily_statistic where pt_number in("KD_JH15#16#_15#_KLQWD") 

AND DATE_FORMAT(stat_date,'%Y-%m-%d') >= '${DATEINMONTH(TODAY(),1)}' AND DATE_FORMAT(stat_date,'%Y-%m-%d') <= '${today()}')b

on a.stat_date = b.stat_date)a

left join

(select a.stat_date,b.空冷前温度平均值 - a.空冷后温度平均值 as 空冷后温降 from

(select stat_date,CONVERT(average_value,DECIMAL(12,2)) as 空冷后温度平均值 from mom_process_index_daily_statistic where pt_number in("KD_JH15#16#_15#_KLHWD") 

AND DATE_FORMAT(stat_date,'%Y-%m-%d') >= '${DATEINMONTH(TODAY(),1)}' AND DATE_FORMAT(stat_date,'%Y-%m-%d') <= '${today()}')a

left join

(select stat_date,CONVERT(average_value,DECIMAL(12,2)) as 空冷前温度平均值 from mom_process_index_daily_statistic where pt_number in("KD_JH15#16#_15#_KLQWD") 

AND DATE_FORMAT(stat_date,'%Y-%m-%d') >= '${DATEINMONTH(TODAY(),1)}' AND DATE_FORMAT(stat_date,'%Y-%m-%d') <= '${today()}')b

on a.stat_date = b.stat_date)b

on a.stat_date = b.stat_date

order by a.stat_date asc