Question

我有一张桌子：

Order_Pairs
----
id
store_id
order_id_buy (References id of order)
order_id_sell (References id of order)

还有第二张表

CREATE OR REPLACE FUNCTION test_func

RETURNS TABLE
(
jdoc JSON
) AS $$

BEGIN
    WITH i AS (
        SELECT *
        FROM order_pairs
          LEFT OUTER JOIN orders orders_buy ON order_pairs.order_id_buy = orders_buy.id
          LEFT OUTER JOIN orders orders_sell ON order_pairs.order_id_sell = orders_sell.id
        WHERE order_pairs.store_id = 1
    )

    SELECT
        ARRAY_TO_JSON(ARRAY_AGG(i.*))
    FROM i;
END; $$ LANGUAGE plpgsql

我想创建一个查询，我可以获取买卖的两个订单记录。

ARRAY_TO_JSON(ARRAY_AGG(i.*))

这很有效。除非程序返回

let headerStyle = {
        backgroundImage : "url('about.jpg')"
    };

我遇到与常见列名称（orders.id）

的重叠

我能够让每个连接记录在提取的orders_buy和orders_sell列名中追加一个字符或字段吗？

Answer 1

此处假设您只需获取有关每个order_pair记录的完整详细信息。

输入数据：

select * from orders;
 id | amount | price 
----+--------+-------
  1 |     10 |   100
  2 |     20 |   200
(2 rows)

select * from order_pairs;
 id | store_id | order_id_buy | order_id_sell 
----+----------+--------------+---------------
  3 |       10 |            1 |             2
  4 |       20 |            1 |             1
(2 rows)

功能：

-- get order pair details by Store Id
CREATE OR REPLACE FUNCTION get_order_pair_details(storeid INTEGER) RETURNS TABLE (jdoc JSON) AS $$
BEGIN
    RETURN QUERY
    WITH q AS (SELECT
                 op.id AS order_pair_id,
                 -- buyer info
                 ob.id AS buyer_id,
                 ob.price AS buyer_price,
                 ob.amount AS buyer_amount,
                 -- seller info
                 os.id AS sell_id,
                 os.price AS sell_price,
                 os.amount AS sell_amount
              FROM order_pairs op
              LEFT JOIN orders ob ON ob.id = op.order_id_buy
              LEFT JOIN orders os ON os.id = op.order_id_sell
              WHERE op.store_id = storeid)
   SELECT array_to_json(array_agg(q.*)) FROM q;
END;
$$ LANGUAGE plpgsql;

结果：

select get_order_pair_details(10) as result;
                                                        result                                                        
----------------------------------------------------------------------------------------------------------------------
 [{"order_pair_id":3,"buyer_id":1,"buyer_price":100,"buyer_amount":10,"sell_id":2,"sell_price":200,"sell_amount":20}]
(1 row)

Postgres将两条记录连接到一条记录上的两个引用

1 个答案: