在MySQL中使用字段的最有效方法是什么？

I have the following query:

我有以下查询:

SELECT DATE(utimestamp) as utimestamp, name, data*2000000 from tData 
where utimestamp BETWEEN '2016-01-01 00:00:00' AND '2016-04-16 00:00:00' 
AND name = 'Valor2' and data>20
group by YEAR(utimestamp), MONTH(utimestamp), name 
union
SELECT DATE(utimestamp) as utimestamp, name, data*0.1 from tData 
where utimestamp BETWEEN '2016-01-01 00:00:00' AND '2016-04-16 00:00:00' 
AND name = 'Valor1' and data>20 
group by YEAR(utimestamp), MONTH(utimestamp), name 
order by utimestamp asc
SELECT