Re: Thermodata query problem

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Dear Fish:

Is there any place where it is recorded what time a Logger is in any
particular Location? If so, this could be associated through the date/time
of the readings. Could someone begin recording this and we could add that
table to the database? Is there any way you can look at the data and tell
from the data what the locations are?

You say the Readings table does contain all the locations, but does it
record the date and time or any other way to make an association.

Tom Ellison


"fishcakes" <fishcakes@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:FAF6DCC5-2583-4DD0-BAE9-FB512714A78A@xxxxxxxxxxxxxxxx
I have a program (Thermodata Suite) that has been designed to automatically
download information from temperature data recorders (i buttons). The
default
database with this program is an ACCESS database. It has 3 tables:
Loggers - this table records information about each logger using LoggerID
as
the primary key. It has only one row for each logger that is used for the
study and a field for the LoggerLocation.
Readings - This table has one row for each time a logger is downloaded
into
the database. The primary key is ReadingID, another field for LoggerID
(links
with referential integrity to the Loggers table) and also has its own
field
for the LoggerLocation. This table also has the reading date and time, and
the date and time of the start and end of the logging period for each time
a
logger is downloaded.
LogData - This contains the actual logged temperature data. It has a
primary
key that is made up of the LoggerID and the date/time field and is linked
only to the Loggers table through LoggerID. This table does not contain
any
information regarding the ReadingID for the downloaded data (unfortunately
?
).

This database structure works fine if each logger is only used in one
location. However, we have used the same logger in different locations.
The
location field in the Loggers table contains only the most recently used
location. The Readings table contains all of the locations each logger was
used. I need to write a query that gives me the actual location that the
temperature data was collected for each logger (LoggerID) - ie the
location
information from the Readings table, not the Loggers table - but these two
tables are not directly linked in any way. When I make this query, with
all
three tables in the design, I can not get it to give me anything.

Does anyone know how I could write such a query?


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