I edit my question to be more clear. the last answers were not helpful for me, maybe I did not ask well my question.
I have a file of nodes and a file of polylines. In my file polylines, I have 2 fields, "NODEA" and "NODEB". In my node file, I have a unique "identifier" field for each node. I want to retrieve with a small line of code the identifier of the node at each end of my polyline.
I try this query but no results.
select id, (select id_arret from noeuds n where st_within(st_startpoint(p.geometry), st_buffer(n.geometry, 1))) n_deb, (select id_arret from noeuds n where st_within(st_endpoint(p.geometry), st_buffer(n.geometry, 1))) n_fin from polylignes p;
"My purpose is to get for each line of the multiline the start and the end node of a line and to fill in 2 colomuns of my multiline table the good node."