we are currently looking at migrating our company data historian over to InfluxDB. We have a Tag called 'tagname' and I would like to run a query to return a list of tagnames, how do I do this? Is this even possible? I have tried the following which seems logical to me coming from a SQL background however all this returns is an empty set:
q=SELECT "tagname" FROM "companyname"."autogen"."lvdata"
'companyname' is a placeholder for actual schema content.
I then tried to look for the last value of each tagname:
q=SELECT "tagname", LAST("value") FROM "companyname"."autogen"."lvdata" WHERE TIME >= '1970-01-01 00:00:00' AND time < '2023-08-14 00:00:00'
but this just returned a single value:
name,tags,time,tagname,last lvdata,,1672271400000000000,tagname,248.564
Kind Regards Paul.
There are schema exploring queries that might be better for this, like SHOW TAG VALUES, eg:
SHOW TAG VALUES ON companyname WITH KEY = "tagname"
But I'd expect your query to work as well.