Question

我有两个名称为raspi_E和raspi_F的表，其结构和列相同 id，address，device_time。

raspi_E表中有多个行具有相同的地址，但我想要最旧的行（相对于时间而言）。

例如，我的地址23多次有device_time个值2014-08-02 16:00:00，2014-08-02 16:00:02，2014-08-02 16:00:04，我想要包含最早device_time的行{1}}，即2014-08-02 16:00:00

同样地，在raspi_F表中，我有多个具有相同地址的行，我必须得到最旧的，在上面的示例中将是2014-08-02 16:10:00。

现在，我需要在时间23与raspi_E的{{1}}地址2014-08-02 16:00:00以及我raspi_F的同一地址23加入最早的设备标记{{1} }}

我尝试使用以下查询：

2014-08-02 16:10:00

使用上述查询时出现以下错误

1064 - 您的SQL语法出错;检查与MySQL服务器版本对应的手册，以获得正确的语法靠近＆＃39; WHERE（raspi_E.device_time BETWEEN＆＃39; 2014-07-31 16：00：00＆＃39; AND ＆＃39; 2014-07-31 16：10：0＆＃39;在第1行

我使用下面的查询来获取raspi_E中最旧的行值，并且它工作正常。

SELECT raspi_E.address, MIN(raspi_E.device_time) 
    AS time_D , MIN(raspi_F.device_time) 
    AS time_E 
WHERE (raspi_E.device_time BETWEEN '2014-07-31 16:00:00' AND 
       '2014-07-31 16:10:00' GROUP BY raspi_E.address) AND 
       (raspi_F.device_time BETWEEN '2014-07-31 16:03:00' AND 
        '2014-07-31 16:25:00' GROUP BY raspi_F.address) 
       AND raspi_E.address=raspi_F.address

Answer 1

您错过了FROM条款和JOIN：

SELECT raspi_E.address, 
MIN(raspi_E.device_time) AS time_D , 
MIN(raspi_F.device_time) AS time_E 
WHERE (raspi_E.device_time BETWEEN '2014-07-31 16:00:00' AND '2014-07-31 16:10:00' GROUP BY raspi_E.address) AND (raspi_F.device_time BETWEEN '2014-07-31 16:03:00' AND '2014-07-31 16:25:00' GROUP BY raspi_F.address) AND raspi_E.address=raspi_F.address

应该是：

SELECT raspi_E.address, 
MIN(raspi_E.device_time) AS time_D , 
MIN(raspi_F.device_time) AS time_E 
FROM raspi_E 
INNER JOIN raspi_F USING <Whatever_key>
WHERE (raspi_E.device_time BETWEEN '2014-07-31 16:00:00' AND '2014-07-31 16:10:00' GROUP BY raspi_E.address) AND (raspi_F.device_time BETWEEN '2014-07-31 16:03:00' AND '2014-07-31 16:25:00' GROUP BY raspi_F.address) AND raspi_E.address=raspi_F.address

Answer 2

因为你在哪里/分组时遇到问题...这应该可以帮到你......

SELECT
      OldestE.Address,
      OldestE.ETime,
      OldestF.FTime
   from 
      ( SELECT 
              E.address, 
              MIN(E.device_time) ETime
           from
              raspi_E E
           where
              E.Device_Time between '2014-07-31 16:00:00' AND '2014-07-31 16:10:00'
           group by
              E.address ) OldestE
      JOIN ( SELECT 
              F.address, 
              MIN(F.device_time) FTime
           from
              raspi_F  F
           where
              F.device_time BETWEEN '2014-07-31 16:03:00' AND '2014-07-31 16:25:00' 
           group by
              F.address ) OldestF
         ON OldestE.Address = OldestF.Address

mysql语句中的错误是什么？

2 个答案: