I've rethought the interpolation strategy. It's not important to be able to look up any timestamp, just the timestamps that actually have values in at least one table. Let's say I have N tables, each with a timestamp as primary key. For instance:
tab1: timestamp|value1|value2 1328873000|1|2 1328873100|3|4 1328873200|5|6 tab2: timestamp|value3 1328873050|7 1328873150|8 1328873250|9 tab3: timestamp|value4|value5|value6 1328873075|10|13|16 1328873175|11|14|17 1328873275|12|15|18 First, I'd like to merge all tables to create one single table with every timestamp and every value. That is, it will have the timestamps that I get by: SELECT timestamp FROM tab1 UNION SELECT timestamp FROM tab2 UNION SELECT timestamp FROM tab3; So the resulting table should be: timestamp|value1|value2|value3|value4|value5|value6 1328873000|1|2| | | | 1328873050| | |7| | | 1328873075| | | |10|13|16 1328873100|3|4| | | | 1328873150| | |8| | | 1328873175| | | |11|14|17 1328873200|5|6| | | | 1328873250| | |9| | | 1328873275| | | |12|15|18 The resulting table will have a lot of NULLs. Next, I'd like to fill out all NULLs by using linear interpolation. But, first things first, how can I merge my tables to get the combined table with NULLs? I've been playing with JOIN and UNION, but I'm afraid my SQL experience is very limited, so I got stuck at this one. In reality I have 7 tables to be merged with a lot of columns (perhaps 100 in all) and up to a million rows, so if an SQL statement to do this sounds unrealistic, that would be a good answer as well. Thanks, -- Steinar Midtskogen _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
