MySQL将两个查询合并为一个查询

Question

I have two working queries. The first one selects the observed temperatures of a given month. The second selects the normal average for each day of that month.

SELECT data, Tmax, Tmin, Mitjana, Pluja 
FROM $estacio 
WHERE data BETWEEN '2014-03-01' AND '2014-03-31'

---

SELECT data, round(avg(Mitjana),1) 
FROM $estacio 
WHERE month(data)='03' 
group by day(data), month(data) 
order by data

I'm trying to find the difference between the observed avg and the normal avg and insert into the first query as a new column. (Mitjana is mean)

Answer 1

Simply added the second query to the first one.

SELECT data, Tmax, Tmin, Mitjana, Pluja, (
  (SELECT NormalAvg FROM
    (SELECT data, round(avg(Mitjana),1) AS NormalAvg FROM $estacio
     WHERE month(data)='03'
     group by day(data), month(data) order by data) AS NormalAvgList
   WHERE NormalAvgList.data=est.data LIMIT 1)-Mitjana) AS Diff
  FROM $estacio AS est WHERE data BETWEEN '2014-03-01' AND '2014-03-31'

Tested with SQL Fiddle .