Hi all,
I am trying to do something unusual (for me) and I can't quite
find the relevant part in the documentation (no mention to joins
in the insert section, or the index).
I want to get a list of data sources with the corresponding data,
if the data exists, or with null, if the data doesn't. But anyway
I need the data sources (all of them).
So I have tried:
select source_name,data_value from source,data where data_source_id=source_id
but it lacks those rows where there is no data in "data" table.
I have also tried:
select source_name,data_value from source,data where data_source_id=source_id union select source_name,source_id,NULL
fromsource,data
This is a bit better, in the sense that I get back all I need, but there
are too many lines: when there is data, I get the line with the data value
and also with NULL.
I strongly suspect that there is a more elegant way of doing it:
a solution or pointers to relevant online litterature would be welcome.
Thanks,
Jean-Marc Libs
--
Jean-Marc Libs, ingénieur INTERNET/INTRANET
Actimage 1 rue St Leon F-67000 STRASBOURG http://www.actimage.net
Professionnel : jeanmarc@actimage.fr
Lieu de travail : jml@obs.coe.int
