[postgis-users] Question about st_difference

[G. van Es]

Hello Group,

About st_difference I've seen several topics but unfortunately with none of them I could solve my problem.

What I want to do is subtract one layer from the other. I could simplify this down to the following;

Tbl_a contains 1 record
"POLYGON(((168119.443682473 451093.811197312,197555.469699649 451093.811197312,197555.469699649 437539.54805452,168119.443682473 437539.54805452,168119.443682473 437539.54805452,168119.443682473 451093.811197312)))"

Tbl_b contains 2 records of which both intersects with the object in tbl_a

"POLYGON(((171424.484910418 453680.34544058,171424.484910418 435697.56759188,174568.140889894 435697.56759188,174568.140889894 453680.34544058,174568.140889894 453680.34544058,171424.484910418 453680.34544058)))"

"POLYGON(((184904.90800885 453627.063135843,184904.90800885 435644.285287143,188048.563988327 435644.285287143,188048.563988327 453627.063135843,188048.563988327 453627.063135843,184904.90800885 453627.063135843)))"

The result I'm looking for is the object of tbl_a abstracted with both objects from tbl_b, since they are both intersecting. In this example the result should be 3 squares since it is cut twice by tbl_b.


Does anyone know a solution for this?

Many thanks in advance,

Ge