How to Select linestring outside multipolygon

[giuseppe]

I'm going crazy about this task that seems to be east but every time don't work!

While intersect a multilinestring with a polygon is very easy :

CREATE TABLE tabl as

SELECT a.1, a.2, ....

st_multi(st_intersects(a.geometry,s.geom))as geom

from t1 a as a, t2 as s

where

st_intersects(a.geometry,s.geom)=1 and

 a.ROWID IN (

    SELECT ROWID 

    FROM SpatialIndex

    WHERE f_table_name = 't1' 

        AND search_frame = s.geom) 

The opposite seems to be very difficult: I need to find the part of the multiline outside the multipolygos.

I've tried everything I'm able to use (Indeed not much) without success.

Any suggestion?