i've a problem with a trigger in postgres. i can do the query but i don't know to development a trigger. the example query is:

select schemaA.table1.value
from schemaB.table2
on
st_contains(schemaB.table2.geom,schemaA.table1.geom)

where geomA is a point geometry and geomB is a polygon geometry.

Can i help me please?

Best