对于c9，PostgreSQL应该像在DECLARE部分中那样使用p_plan_version_id的值，还是像在OPEN c9部分中那样使用p_plan_version_id的值？为了解决这个歧义，你需要在打开游标时传递两个参数：

DECLARE
   c9 CURSOR (p_product_code varchar, p_pvi numeric) FOR
      SELECT product_code,
             terminal_code,
             quantity
      FROM product_stock pos
      WHERE pos.plan_version_id = p_pvi
        AND pos.product_code    = p_product_code;
BEGIN
   OPEN c9('OIL', p_plan_version_id);
   ...
END;

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下面是一个完整的例子来证明这一点：

CREATE FUNCTION sample(upper_limit bigint) RETURNS SETOF bigint
   LANGUAGE plpgsql AS
$$DECLARE
   c CURSOR (l bigint, u bigint) FOR
      SELECT * FROM generate_series(l, u) AS g(c);
   r record;
BEGIN
   OPEN c(1, upper_limit);
   LOOP
      FETCH c INTO r;
      EXIT WHEN NOT FOUND;

      RETURN NEXT r.c;
   END LOOP;
END;$$;

SELECT * FROM sample(10);

 sample 
════════
      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
(10 rows)

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