Working with Cursors

DECLARE c CURSOR FOR SELECT id, name FROM customers ORDER BY id;

OPEN c;

FETCH c INTO id_var, name_var;
EXIT WHEN NOT FOUND;

CLOSE c;

DECLARE c CURSOR (min_total int) FOR
   SELECT * FROM orders WHERE total_cents >= min_total;
OPEN c(10000);

FOR r IN c LOOP
   PERFORM process(r);
END LOOP;
-- or implicit query loop:
FOR r IN SELECT ... LOOP ... END LOOP;

DECLARE c SCROLL CURSOR FOR SELECT ... ;
FETCH PRIOR FROM c;
FETCH ABSOLUTE 100 FROM c;

DECLARE c NO SCROLL CURSOR FOR SELECT ... ;     -- forward-only, cheaper

BEGIN;
DECLARE c CURSOR WITH HOLD FOR SELECT ... ;
COMMIT;        -- cursor persists; result materialized
FETCH 100 FROM c;
CLOSE c;

DECLARE c CURSOR WITHOUT HOLD FOR ... ;   -- default; auto-closed at COMMIT

MOVE FORWARD 50 IN c;      -- skip without fetching
MOVE ABSOLUTE 0 IN c;      -- rewind

FETCH 1000 FROM c;
FETCH FORWARD 500 FROM c;