2

I have seven point shapefiles at the same geographic location with three common fields ("ID", "name2", "name3") and a fourth field, ("uni_value") that is unique to each shapefile.

All seven shapefiles have been produced by a QGIS Graphical Modeler workflow and would like to combine all layers into a single table for export into a PostgreSQL database.

Example tables below:

Point Layer 1
    ID | name2 | name3 | unique_value1 
Point Layer 2
    ID | name2 | name3 | unique_value2 
Point Layer 3
    ID | name2 | name3 | unique_value3 
.
.
.

Point Layer 7
    ID | name2 | name3 | uni_value7

Final Merged table:

ID | name2 | name3 | uni_value1 | uni_value2 | ... | uni_value7 
0

2 Answers 2

1

There is a possibility using a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer....

Let's assume there are two point layers one called 'points1' and second called 'points2', see image below.

input

With the following query, it is possible to combine all layers into a single table.

SELECT
    "ID",
    "name2",
    "name3",
    "unique1" AS "unique1",
    NULL AS "unique2",
    geometry
FROM
    "points1"
UNION ALL
SELECT
    "ID",
    "name2",
    "name3",
    NULL AS "unique1",
    "unique2" AS "unique2",
    geometry
FROM
    "points2"

The output point layer with its attribute table will look like:

result

1
  1. Menu Processing > Toolbox > Merge Vector Layers.

  2. Field calculator: create a new string (text) field with this expression: concatenate( to_string(unique_value1), concatenator:=',', group_by:=name2 || name3).

  3. Menu Processing > Toolbox > Delete duplicate Geometries.

2
  • Thank you for answer, but I was looking to put each unique field value into a seperate field instead of one field separated by commas.
    – MJM
    Commented May 4, 2022 at 19:28
  • OK, I see. So based on this solution, this is only possible to it one by one for each layer - which is probably not what you want.
    – Babel
    Commented May 4, 2022 at 19:38

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