mysql获取具有限制的多个列的平均值

mysql获取具有限制的多个列的平均值,mysql,Mysql,我试图从3列中平均得到最后60个项目,但我得到一个错误: #1248 - Every derived table must have its own alias 以下是查询: SELECT AVG( Sensor1 ) , AVG( Sensor2 ) , AVG( Sensor3 ) FROM ( SELECT Sensor1, Sensor2, Sensor3 FROM temperatur ORDER BY Zeit DESC LIMIT 0 , 6

我试图从3列中平均得到最后60个项目,但我得到一个错误:

#1248 - Every derived table must have its own alias
以下是查询:

SELECT AVG( Sensor1 ) , AVG( Sensor2 ) , AVG( Sensor3 ) 
FROM (

    SELECT Sensor1, Sensor2, Sensor3
    FROM temperatur
    ORDER BY Zeit DESC 
    LIMIT 0 , 60
)

我对别名很迷茫,我相信..

MySQL在所有派生表和子查询上都需要一个别名,而在右括号后缺少别名:

SELECT AVG( d.Sensor1 ) , AVG( d.Sensor2 ) , AVG( d.Sensor3 ) 
FROM 
(
    SELECT Sensor1, Sensor2, Sensor3
    FROM temperatur
    ORDER BY Zeit DESC 
    LIMIT 0 , 60
) d --- add this

我猜是sytax,但我相信你需要这样的东西:

选择平均值(T.Sensor1)、平均值(T.Sensor2)、平均值(T.Sensor3) 从(


)T

谢谢,我想现在我明白了!:)
SELECT Sensor1, Sensor2, Sensor3
FROM temperatur
ORDER BY Zeit DESC 
LIMIT 0 , 60