Hi everyone!
I'm a starter on SQL / SQLite and there is some problem I'd solve in software but I have the feeling this can be done using a query. If somebody can help me out I'd be glad - I have the feeling there is something to learn for me here. Here goes: Schema of DB (simplified): - Oper (string) - Product (string) - Category (string) - Name (string) - CreateTS (Timestamp) - Value (Double) Primary keys are Oper, Product, Category, Name and CreateTS Basic usage is dumping "measurements" as doubles into the table. This happens usually in larger groups like - "op", "cat", "product", "m1", 1.234, 2009-11-24 09:49:20.25 - "op", "cat", "product", "m2", 1.234, 2009-11-24 09:49:20.25 - "op", "cat", "product", "m3", 1.234, 2009-11-24 09:49:20.25 - "op", "cat", "product", "m4", 1.234, 2009-11-24 09:49:20.25 Now suppose this has happend a lot so that m1 to m4 is present quite often but of course with differing timestamps in CreateTS (it's a primary key after all). What I could not figure out: Suppose I want to select rows by "op", "cat", "product" and get all measurements "m1" to "m4" with the latest timestamp in CreateTS. So for a set of measurements identified by everything but their name select the latest rows as defined by the timestamp. Can I do that in SQL in one query? Any help is very much appreciated! (I know this might be a simple SQL question for most here and I should better get some training on all that. But if somebody can help a bit with that I'd sure be glad!) kind regards Florian _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
