The first recursive view definition demonstrates the valid use of an ordered analytic function, which is highlighted in bold typeface. The usage is valid because it is within the seed statement rather than the recursive statement of the definition.
CREATE RECURSIVE VIEW reachable_from (source, destination, cost,
depth) AS (
SELECT source, destination, MSUM(flights.cost, 25, flights.destination), 0 AS depth
FROM flights
UNION ALL
SELECT in1.source, out1.destination, in1.cost + out1.cost,
in1.depth + 1
FROM reachable_from in1, flights AS out1
WHERE in1.destination = out1.source
AND in1.depth <= 100);
The second recursive view definition demonstrates a non-valid use of the same ordered analytic function, which is again highlighted in bold typeface. The usage is not valid because it is within the recursive statement rather than the seed statement of the definition.
CREATE RECURSIVE VIEW oaf_problem (source, destination, mcost,
depth) AS (
SELECT source, destination, MSUM(cost, 25, destination),
0 AS depth
FROM flights
UNION ALL
SELECT in1.source, out1.destination,
MSUM(in1.mcost + out1.cost, 25, out1.destination),
in1.depth + 1
FROM oaf_problem AS in1, flights AS out1
WHERE in1.destination = out1.source
AND in1.depth <= 100;