Hi, you are simply facing the SQL standard behavior of the | operator when it compares something to a NULL value, the whole result will be NULL. In SQL, you can avoid that by wrapping each value in a "coalesce(myvalue, '')" that will replace NULL by an empty string.
In QGIS, you can also use the "+" operator, and this one does not sends a NULL like the pipe operator. Far more simple indeed, but less portable to pure SQL . Cheers Régis 2016-12-21 3:33 GMT+01:00 damos <[email protected]>: > HI I am trying to do a nested case statement for a labelling task. > I have a list of mines of varying sizes with different commodities and > would > like to label with the name of the mine and the amount of each commodity at > the mine in a new line below the name. I only want to label the mines that > I > have decided are signifcant and for this I have made a new column in my > table called significant. > My difficulty is that not all mines have the same commodities, for example > one mine has copper (Cu) and no lead(Pb), while another has both. yet > another will only have Pb. > i can easily label all of the sigificant mines and their copper amoutns > with > a suffix of kt Cu using this code: > > case when "signifcant" = 'yes' then title( "Name" ) || '\n' || > case > when "Cu_e_t" <1 then '' else round("Cu_e_t"/1000,0) || 'Kt Cu' end else > null end > > however if I then try to add in the Pb amounts like this; > case when "signifcant" = 'yes' then title( "Name" ) || '\n' || > case > when "Cu_e_t" <1 then '' else round("Cu_e_t"/1000,0) || 'Kt Cu' end || > case when "Pb_e_t" <1 then '' else round("Pb_e_t"/1000,0) || 'Kt Pb' end > else null end > > I lose all of the Cu only mines and only get labels for those with Cu and > Pb > or just Pb. > I understand that I am doing something wrong with the nested case > statements, but cant figure out what. > > any help would be much appreciated. > int the mean time I am going back to do the formula in excel where I am > capable. > > > > > -- > View this message in context: http://osgeo-org.1560.x6. > nabble.com/using-nested-case-statements-in-labelling-tp5300779.html > Sent from the Quantum GIS - User mailing list archive at Nabble.com. > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
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