That's why you make a table for every device or every measurement, and then use a view to consolidate it. With updatable views, there's no excuse not to.
-- Brandon Aiken CS/IT Systems Engineer -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve Crawford Sent: Friday, February 23, 2007 1:04 PM To: Mark Walker Cc: pgsql-general@postgresql.org Subject: Re: [GENERAL] postgresql vs mysql Mark Walker wrote: > I'm not sure what you're trying to do but, it appears that you database > design is incorrect. What you need is something like > > CREATE TABLE temp_readings > ( > _date Date, > temperature double, > source varchar(20), > ) > > No reading, no record. Are you suggesting that you would have a weekly > set of records for each row? > > CREATE TABLE temp_readings > ( > weekstart date, > sun double, > mon double, > tues, double > etc > ) > > Not such a great way to do it. Ummm, I'm not trying to make a temperature database. I was responding to the previous poster with an extremely simple example of usefulness of the _concept_ of "null". I'm afraid I hadn't considered the possibility that it would be mistaken as an example of an actual table. But since you bring it up, simply omitting rows isn't necessarily an option. A common scenario for weather observation is to take regular snapshots or a bunch of measurements (air-temperature, humidity, wind-speed, soil-temperature, leaf-wetness, UV radiation, etc.) which can easily be represented in a table with a timestamp and a column for each of the measurements. In a modular weather station where a specific instrument can be out of service, one or more of those measurements could be missing (null) for a period of time while the remaining measurements are still being inserted. Cheers, Steve ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org/ -------------------------------------------------------------------- ** LEGAL DISCLAIMER ** Statements made in this e-mail may or may not reflect the views and opinions of Wineman Technology, Inc. or its employees. This e-mail message and any attachments may contain legally privileged, confidential or proprietary information. If you are not the intended recipient(s), or the employee or agent responsible for delivery of this message to the intended recipient(s), you are hereby notified that any dissemination, distribution or copying of this e-mail message is strictly prohibited. If you have received this message in error, please immediately notify the sender and delete this e-mail message from your computer. ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
