在plpgsql函數中選擇並訪問其字段的數據類型

Question

我在Postgres 9.5數據庫中有以下表格：

product

 Column         |            Type             |                       Modifiers
----------------+-----------------------------+-----------------------------------------------------
id              | integer                     | not null default nextval('product_id_seq'::regclass)
name            | character varying(100)      |
number_of_items | integer                     |
created_at      | timestamp without time zone | default now()
updated_at      | timestamp without time zone | default now()
total_number    | integer                     |
provider_id     | integer                     |  
 Indexes:
    "pk_product" PRIMARY KEY, btree (id)
 Foreign-key constraints:
   "fk_product_provider" FOREIGN KEY (provider_id) REFERENCES provider(id)

我們也有

provider

     Column    |            Typ         |           Modifiers
  -------------+------------------------+------------------------------
   id          |       integer          | not null default nextval('property_id_seq'::regclass)
   name        |       text             |
   description |       text             |
   created_at  | timestamp without time zone | default now()
   updated_at  | timestamp without time zone | default now()
 Indexes:
      "pk_provider" PRIMARY KEY, btree (id)

我實現了一個plpgsql function ，該plpgsql function應該找到provider某些特定產品並遍歷它們

      products = select u_id, number_of_items from product 
          where provider_id = p_id and total_number > limit;
      loop 
          //here I need to loop through the products 

      end loop;

問題我應該為products變量聲明哪種data type以便將查詢的產品存儲到其中？ 還有以后我應該如何訪問它的id或number_of_items列？

Answer 1

在PostgreSQL中，創建表還定義了一個與表同名的復合數據類型。

您可以使用該類型的變量：

DECLARE
   p product;
BEGIN
   FOR p IN SELECT product FROM product WHERE ...
   LOOP
      [do something with "p.id" and "p.val"]
   END LOOP;
END;

或者，您可以為所需的各個字段使用幾個變量（可能更好）：

DECLARE
   v_id integer;
   v_val text;
BEGIN
   FOR v_id, v_val IN SELECT id, val FROM product WHERE ...
   LOOP
      [do something with "v_id" and "v_val"]
   END LOOP;
END;