Another solution is to use the ST_Union() inside of the query, because features from a "cut" layer need to become one geometry (of type MULTIPOLYGON). This idea was taken from this thread : More on cutting polygons with polygons, in PostGIS.

Let's assume there are two polygon layers called 'grid_test' (green) with nine features and 'grid_test2' (orange) with five features in it, see image below.

So, your query may look like this:

WITH union_gd2 AS ( SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) SELECT gd1.id, st_difference(gd1.geometry, ugd2.geometry) AS geometry FROM "grid_test" AS gd1, "union_gd2" AS ugd2 WHERE st_isvalid(st_difference(gd1.geometry, ugd2.geometry)) 

or like this:

SELECT gd1.id, st_difference(gd1.geometry, union_gd2.geometry) AS geometry FROM "grid_test" AS gd1, (SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) AS union_gd2 WHERE st_isvalid(st_difference(gd1.geometry, union_gd2.geometry)) 

and then get the final output

Another solution is to use the ST_Union() inside of the query (it was also mentioned in
@geozelot's comment), because features from a "cut" layer need to become one geometry (of type MULTIPOLYGON). This idea was taken from this thread : More on cutting polygons with polygons, in PostGIS.

Let's assume there are two polygon layers called 'grid_test' (green) with nine features and 'grid_test2' (orange) with five features in it, see image below.

So, your query may look like this:

WITH union_gd2 AS ( SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) SELECT gd1.id, st_difference(gd1.geometry, ugd2.geometry) AS geometry FROM "grid_test" AS gd1, "union_gd2" AS ugd2 WHERE st_isvalid(st_difference(gd1.geometry, ugd2.geometry)) 

or like this:

SELECT gd1.id, st_difference(gd1.geometry, union_gd2.geometry) AS geometry FROM "grid_test" AS gd1, (SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) AS union_gd2 WHERE st_isvalid(st_difference(gd1.geometry, union_gd2.geometry)) 

and then get the final output

References:

• Select empty Postgis (Postgresql) geometry column

Another solution is to use the ST_Union inside of the query. This idea was taken from this thread : More on cutting polygons with polygons, in PostGIS

Let's assume there are two polygon layers called 'grid_test' (green) with nine features and 'grid_test2' (orange) with five features in it, see image below.

So, your query may look like this:

WITH union_gd2 AS ( SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) SELECT gd1.id, st_difference(gd1.geometry, ugd2.geometry) AS geometry FROM "grid_test" AS gd1, "union_gd2" AS ugd2 WHERE st_isvalid(st_difference(gd1.geometry, ugd2.geometry)) 

or like this:

SELECT gd1.id, st_difference(gd1.geometry, union_gd2.geometry) AS geometry FROM "grid_test" AS gd1, (SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) AS union_gd2 WHERE st_isvalid(st_difference(gd1.geometry, union_gd2.geometry)) 

and then get the final output

Another solution is to use the ST_Union() inside of the query, because features from a "cut" layer need to become one geometry (of type MULTIPOLYGON). This idea was taken from this thread : More on cutting polygons with polygons, in PostGIS.

Let's assume there are two polygon layers called 'grid_test' (green) with nine features and 'grid_test2' (orange) with five features in it, see image below.

So, your query may look like this:

WITH union_gd2 AS ( SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) SELECT gd1.id, st_difference(gd1.geometry, ugd2.geometry) AS geometry FROM "grid_test" AS gd1, "union_gd2" AS ugd2 WHERE st_isvalid(st_difference(gd1.geometry, ugd2.geometry)) 

or like this:

SELECT gd1.id, st_difference(gd1.geometry, union_gd2.geometry) AS geometry FROM "grid_test" AS gd1, (SELECT ST_Union(gt2.geometry) as geometry FROM "grid_test2" AS gt2 ) AS union_gd2 WHERE st_isvalid(st_difference(gd1.geometry, union_gd2.geometry)) 

and then get the final output