Hi group,
i build a model to save measurement data. a measurement entry has
always a channel (that is the source where the data comes from), a
value (for example 1.04), a unit (for example m/s or Hz) and a
timestamp.
The timestamp and the channel are together unique. every channel can
only have one data entry for one timestamp.
i have the following model:
class Data(models.Model):
datetime = models.DateTimeField(help_text='the date and time of
the measurement value', db_index=True)
channel = models.CharField(help_text='the channelname',
max_length=20, db_index=True)
value = models.FloatField(help_text='the measurement value',
db_index=True)
unit = models.CharField(help_text='the unit of the measurement
value', max_length=20, db_index=True)
class Meta:
unique_together = [('datetime', 'channel')]
now, i want to have a query to get the following data-table:
datetime channel1 unit1 channel2
unit2
2009-01-01 00:00:00 10.0 m/s 1000 Hz
2009-01-01 00:00:10 15.0 m/s 1040 Hz
2009-01-01 00:00:20 16.0 m/s 1563 Hz
Is something like this possible with django?
i know that i can get all data ordered by date and the use python to
get a datastructure like the described table. but i want to do it with
the database because i think it's much faster.
any ideas how to do this?
Best regards,
tom
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