[Qgis-user] Can't accomplish comparisions between different Map Layer Table's

[oisin.kelly.wild at gmail.com]

You definitely need to define the layer for each attribute (except the current layer).

You also need a way to find the comparable record, e.g. 
(i) with a common id (use getfeature() to access attribute) or
(ii) spatially use one of the overlay functions. 

Oisin 

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On 14 May 2024, 19:52, at 19:52, Guillermo Parra via QGIS-User <qgis-user at lists.osgeo.org> wrote:
>Hi,
>I have several tables with the same fields, same grid information, but
>different field data for each one (information from different
>providers, let's say).
>Particularly, I have a field with 0 and 1 which represent if each
>provider have, or not have coverage in that area.
>I want to compare the values of each table to set "1" if at least one
>of the providers have coverage in each area, or "0" if None of them
>have it, so I used the field calculator and the expression builder with
>this sql statement:
>if( 'H3centr_h9_cobcubierto'  = 1 OR 'H3centr_h9_cobcubierto' = 1
>OR'H3centroides_h9_cobGT3D cubierto' = 1
>OR'H3centroides_h9_cob_cubierto'  = '1' OR'H3centr_h9_cob_cubierto' =
>'1' OR'H3cent_cob_cubierto'  = '1' OR"H3centrR9_Tc3D_cubierto"  ='1',
>1, 0)
>The problem is that apparently it is considering only the last field in
>double quotes (which is in the same table that the new column where I
>want to fill the data), and the other fields apparently are beign
>ignored.
>I would guest that it would be better to specify the table and field
>where each data will be taken ( like  if(
>'Table1.H3centr_h9_cobcubierto'  = 1 OR 'Table2.H3centr_h9_cobcubierto'
>= 1 OR... etc.)but when I make double click over each layer field, QGIS
>writes it that way, so I asume it is correct.
>So, if someone have an idea on how I can make it work, I would greatly
>appreciate any suggestion.Thanks,
>Guillermo.
>
>Guillermo Parra Montealegre e-mail: meminp_24 at yahoo.com
>
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