Adding Spatial data from PostGIS database to QGIS Desktop

This post will demonstrate how to add GIS data from a PostGIS database hosted online using QGIS.

This tutorial assumes the user already runs a PostGIS server.

  1. Click on the ‘Add PostGIS Layers’ icon button on the main menu bar. See where cursor pointer ison the screenshot below.



2.First click ‘Connect to select a connection to a PostGIS (Postgres in our own case)



3.A dialog box will pop up prompting you to fill in the sign in credentials for the PostGIS server



4.The database tables will be automatically loaded into the window.

Click to highlight the data table you want to add to QGIS.

Click Add button.



5.In the previous screenshot, note that the SRID column is empty for the data selected.

In this case, a dialog box will pop up and you can select an appropriate CRS for the data. For our demo, its WGS 84



6.The data table is loaded into QGIS as a vector layer as seen on the screenshot below.



Part Two


In this instance, we don’t need all the data on a Table but just a section. We can use the ‘Set filter’option and add only the selection of the data we require.

1.We connect the PostGIS again and select a data table. This table contains the administrativeboundaries of several districts in a State.



2.Our intention is to filter the table and add only the boundary polygon of one of the districts. Click on ‘Set Filter’ button as shown in the screenshot below



3.The Query Builder dialog box opens. Compute a query that will sselect from the table where the nameof the district is IbadanNorth. You can click ‘Test’ to authenticate that there are no errors in the query. Click OK



4.Click ‘Add’ on this window to load the selection into the map canvas of QGIS Desktop



5.The selected district administrative boundary is displayed on the QGIS Desktop map canvas.



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