Adding field in vector layer from attribute table in QGIS

Question

I have an attribute table named 'data.shp' and a vector layer 'pop.shp'.

The 'data.shp' has the following fields "ID", "value1", "value2"

The 'pop.shp' has the "ID" field (same with the 'data.shp')

I want to update 'pop.shp' and add the fields "value1", "value2" from 'data.shp' where "ID" (from 'data.shp') is equal to "ID" (from 'pop.shp').

How could I do that in QGIS?

Have you checked this tutorial Performing Table Joins? Start from Step #12, inclusive. — Taras, Feb 21 '19 at 14:27
Possible duplicate of Joining non-spatial CSV file to spatial data (shapefile) using QGIS?, mainly Nathan W's answer. — Taras, Feb 21 '19 at 14:34
@Taras it seems sql tag was removed. That tag is essential to distinguish Nat's question from the linked one. Thanks! — Kazuhito, Feb 21 '19 at 14:54
@Kazuhito, shall I place it back? However, I did not find out anything related to sql in the gist of the question itself, is not it? Can you clarify this for me, please? — Taras, Feb 21 '19 at 15:04
@Kazuhito I'm not sure the sql tag is that relevant even to the linked questions. The joins can be done without it. — Gabriel, Feb 21 '19 at 15:05
@Taras I see your point. But a tag is important part of the question. — Kazuhito, Feb 21 '19 at 15:05
@GabrielC. In some cases there are multiple possible solutions. A tag can tell us preferred approach. (As Taras says, it is much clear if mentioned in the body of question.) — Kazuhito, Feb 21 '19 at 15:17
@Kazuhito Maybe, but I would say it's a case of X Y Problem. OP might just not have known about how easily joins can be done and expected needing SQL. In any case, clarifying in the question will steer answers towards what he wants. — Gabriel, Feb 21 '19 at 15:42

score 8 · Accepted Answer · edited Feb 21 '19 at 16:24

QGIS has built-in table join capabilities. If you want to add fields from a table (data.shp) into another layer (pop.shp), then go this way:

Right click on pop.shp -> Properties -> Joins -> "+"
Choose relevant layer and key field for the join
Check which fields you want to add
Click OK

The attribute table from your pop.shp layer should now include the data you need. To make this permanent, save the layer as a new file.

Taras · Answer 2 · 2021-11-09T06:43:33.040

4

Another solution implies the usage of a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer....

With the following query, it is possible to update 'pop.shp' and add the fields "value1", "value2" from 'data.shp'.

SELECT
    pop.*,
    data.value1,
    data.value2
FROM
    "pop"
LEFT JOIN "data"
    ON pop.id = data.id

References:

edited Nov 09 '21 at 06:43

answered Feb 21 '19 at 15:20

Taras

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Adding field in vector layer from attribute table in QGIS

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