Based on the initial post, it seems you want all the columns for the latest datetime? If so, I think y'all are working too hard:
Try, SELECT * FROM 'table_name' ORDER BY datetime DESC LIMIT 1 I put the various parts on separate lines for emphasis. I'd have it all on one line, separated by spaces. - The *LIMIT 1* part says give me only one row - The *ORDER BY datetime DESC* part says to sort by datetime, biggest values first - Together, these give the 1 row that has the highest datetime. This should be a very efficient statement since it use core functions and the last record is probably still in MySQL's memory. Dave On Wednesday, November 9, 2016 at 12:59:17 AM UTC-6, Andrew Milner wrote: > > Thanks Gary - done my homework, created a subquery for today's readings > (since MySQL can't have a subquery in a view) and selected from that. > Still do not fully understand the where datetime is null part though - but > it works (down to a second now) > > On Wednesday, 9 November 2016 07:32:46 UTC+2, gjr80 wrote: >> >> The WHERE clause must be satisfied or surely there would be no results at >> all? >> >> As for optimising, that is left as homework... Seriously, you might find >> some info by googling 'SQL optimise left join', quite a few results but a >> bit heavy for me. Sorry but it was a stretch coming up with the query. >> >> Gary >> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
