Hi everyone, I've got a project where I record measurement data for various objects in 15 minute intervals. A simplified table structure could look like:
- objectid Integer - dt DateTime - measurementA Integer - measurementB Integer - measurementC Integer I've got a few thousand different unique objectid's which report measurements every 15 minutes. What I need to do is to figure out, for every day, which hour has the highest value summed up across all objectid's. The first step is just to get the time stamp but later I'd like to retrieve the sum(measurementX) at that particular hour for all objects for a series of dates. Is there a good way to do this? It's not so important that the peak hour is calculated on an hour boundary (given one value every 15 min). A final question... I filter the objects I wish to retrieve data for by means of a WHERE objectid IN (1,2,3,4, ...) Supposed now this IN list contain a number of entries, from a single up to a few thousand, would it be faster to insert these values into a temporary table and then do a JOIN operation during the select? Thanks in advance, Niklas -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
