How to create Point Layers from x/y Data on the fly with PostGIS and QGIS

Sometimes, we just want to visualize the contents of a PostGIS table containing some x/y data but no actual geometries in QGIS. But there the problems arise: We don’t have the right to add a geometry column, the table doesn’t have a suitable ID or OIDs (QGIS demands a unique integer ID) and we can’t or don’t want to mess with the database anyway. Loading the table with “Add PostGIS Layer” will result in a non-spatial layer (or fail if you use an older QGIS versions).

RT Sql Layer Plugin to the rescue!

I presented this plugin in a previous post. It allows you to execute any SQL SELECT statement, even really complex ones. Luckily, this time we don’t need anything fancy, only the two functions row_number() and makepoint():

select  
  row_number() over (order by col1)::int AS my_id,
  col1, 
  col2,
  x, y, 
  makepoint(x,y) as the_geom
from my_table

• PostGIS
• QGIS
• RT Sql Layer
• SQL