选择最后一个值并加入同一个表

Question

我有3个库存容器（AN_S1，AN_S2，AN_S3）。我从PLC读取它们的重量和电机逆变器的状态（QEV1，QEV2，QEV3 [0 = OFF，1 = ON]）。

valore =集装箱的重量（S1，S2，S3）; [0-1]用于逆变器（QEV1，QEV2，QEV3） data_ora是一个时间戳。

所以，每隔5分钟我就读一次PLC变量。我有这张表：

+-----------------------------------+---------+---------------------+ 
| nome        | valore | data_ora   | 
+-----------------------------------+---------+---------------------+ 
| AN_S1        | 3.9725 | 2016-09-06 19:10:05 | 
| AN_S2        | 150.26 | 2016-09-06 19:10:05 | 
| AN_S3        | 207.026 | 2016-09-06 19:10:05 | 
|QEV1        |  0 | 2016-09-06 19:10:05 | 
|QEV2        |  1 | 2016-09-06 19:10:05 | 
|QEV3        |  1 | 2016-09-06 19:10:05 | 
|MARCIA_9       |  0 | 2016-09-06 19:10:05 | 
|MARCIA_10       |  0 | 2016-09-06 19:10:05 | 
| AN_S1        | 0.0005 | 2016-09-06 19:15:06 | 
| AN_S2        | 100.26 | 2016-09-06 19:15:06 | 
| AN_S3        | 977.004 | 2016-09-06 19:15:06 | 
|QEV1        |  0 | 2016-09-06 19:15:06 | 
|QEV2        |  0 | 2016-09-06 19:15:06 | 
|QEV3        |  0 | 2016-09-06 19:15:06 | 
| MARCIA_9       |  0 | 2016-09-06 19:15:06 | 
| MARCIA_10       |  0 | 2016-09-06 19:15:06 | 
| AN_S1        | 367.08 | 2016-09-06 19:20:05 | 
| AN_S2        | 50.26 | 2016-09-06 19:20:05 | 
| AN_S3        | 70135 | 2016-09-06 19:20:05 | 
|QEV1        |  0 | 2016-09-06 19:20:05 | 
|QEV2        |  1 | 2016-09-06 19:20:05 | 
|QEV3        |  1 | 2016-09-06 19:20:05 | 
| MARCIA_9       |  0 | 2016-09-06 19:20:05 | 
| MARCIA_10       |  0 | 2016-09-06 19:20:05 | 
+----------------------------------+---------+----------------------+ 

我想查询有这个。对于每个容器，我想最后更新的重量和它的反相器的状态：

+-----------------------------------+---------+---------------------+ 
| nome        | valore | QEV     | 
+-----------------------------------+---------+---------------------+ 
| AN_S1        | 367.08 | 0     | 
| AN_S2        | 50.26 | 1     | 
| AN_S3        | 70135 | 1     | 
+----------------------------------+---------+----------------------+ 

仅选择最后一个（data_ora是日提交的时间戳）的值（valore）与每个corrispondending QEV值接合。

Answer 1

我不知道whee的QEV会进来，而是要选择最recen时间戳，使用值：

select T1.nome, T1.valore, T1.data_ora 
from Table1 T1 
where data_ora = 
    (select max(T2.data_ora) from Table1 T2 where T1.nome = T2.nome) 
and T1.nome like 'AN%' 

而对于QEV：

select T3.nome, T3.valore as QEV, T3.data_ora 
from Table1 T3 
where data_ora = 
    (select max(T4.data_ora) from Table1 T4 where T3.nome = T4.nome) 
and T3.nome like 'QEV%' 

现在我们加入

select A1.nome, A1.valore, A2.QEV 
from (
    select T1.nome, T1.valore, T1.data_ora 
    from Table1 T1 
    where data_ora = 
     (select max(T2.data_ora) from Table1 T2 where T1.nome = T2.nome) 
    and T1.nome like 'AN%' 
) A1 
inner join (
    select T3.nome, T3.valore as QEV, T3.data_ora 
    from Table1 T3 
    where data_ora = 
     (select max(T4.data_ora) from Table1 T4 where T3.nome = T4.nome) 
    and T3.nome like 'QEV%' 
) A2 
    on A1.data_ora = A2.data_ora