我有两个表,sensor和sensor_desc。我想从上次插入sensor_id的两个表中检索sensor.date和sensor_desc.location。涉及两个表的SQL语句
我试过这段代码不起作用。
cur = con.cursor()
cur.execute("Select sensor_id from sensor order by date desc limit 1")
con.commit()
last= cur.fetchall()
print '%s' %last
cur1= con.cursor()
cur.execute("Select sensor.date, sensor_desc.location from sensor, sensor_desc where sensor.sensor_id= %s AND sensor_desc.sensor_id=%s",(last, last))
con.commit()
lastseen = cur1.fetchall()
print '%s'%lastseen
传感器
+-----------+---------------------+-------+
| sensor_id | date | value |
+-----------+---------------------+-------+
| 12345 | 2015-08-17 10:16:41 | NULL |
| 12345 | 2015-08-17 10:17:29 | NULL |
| 12345 | 2015-08-17 10:18:06 | NULL |
| 12345 | 2015-08-17 13:28:55 | 1 |
| 12345 | 2015-08-17 13:29:49 | 1 |
+-----------+---------------------+-------+
sensor_desc
+-----------+--------------------+-------------+
| sensor_id | description | location |
+-----------+--------------------+-------------+
| 12341 | Motion Sensor | Kitchen |
| 12342 | Motion Sensor | Toilet |
| 12343 | Motion Sensor | Living Room |
| 12344 | Motion Sensor | BedRoom |
| 12345 | Panic Button | NULL |
| 12346 | Temperature Sensor | NULL |
| 12347 | CO2 Sensor | NULL |
+-----------+--------------------+-------------+
它是如何工作的?你期望结果如何?你现在得到什么结果?请编辑问题并添加此信息。 –
请标记您正在使用的语言。我现在的想法是,您需要将两个表加入到一起,按照降序排列的sensor_id的ORDER BY,然后限制为一条记录。 –
@Tyra,请停止删除您的其他问题。我正在准备一个关于在数据库表中存储XBee地址的问题的答案,但是在我提交之前将其删除(两次!)。 – tomlogic