CREATE TABLE "uniform_resource_edge" (
"graph_name" VARCHAR NOT NULL,
"nature" TEXT NOT NULL,
"node_id" TEXT NOT NULL,
"uniform_resource_id" VARCHAR NOT NULL,
"elaboration" TEXT CHECK(json_valid(elaboration) OR elaboration IS NULL),
FOREIGN KEY("graph_name") REFERENCES "uniform_resource_graph"("name"),
FOREIGN KEY("uniform_resource_id") REFERENCES "uniform_resource"("uniform_resource_id"),
UNIQUE("graph_name", "nature", "node_id", "uniform_resource_id")
)