我有一些物品的价格表:
|----------------------------|
| ItemID (INT) | Price (INT) |
|--------------|-------------|
| 1 | 50 |
|--------------|-------------|
| 2 | 36 |
|--------------|-------------|
| 3 | 11 |
|--------------|-------------|
| 4 | 22 |
|--------------|-------------|
| 5 | 54 |
|--------------|-------------|
| 6 | 38 |
|--------------|-------------|
| 7 | 2 |
|--------------|-------------|
| 8 | 1 |
|--------------|-------------|
| 9 | 39 |
|----------------------------|
此表包含大多数实际价格,每小时更新一次(例如)。
我喜欢"推车"在购物车创建时实际购买的商品和价格:
|-------------------------------------------------------|
| CartID (INT) | Items (INTEGER[]) | Prices (INTEGER[]) |
|--------------|-------------------|--------------------|
| 1 | {1,2,3} | {50,25,310} |
|--------------|-------------------|--------------------|
| 2 | {4,5,6} | {1337,20,32} |
|--------------|-------------------|--------------------|
| 3 | {1,9,6,7} | {258,356,711,2} |
|-------------------------------------------------------|
在某些情况下,我必须将此购物车中的价格更新为实际价格。
我的功能(未完成):
CREATE OR REPLACE FUNCTION public.prices_update(startindex integer)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
AS $function$
DECLARE
cart RECORD;
prices INTEGER[];
t RECORD;
BEGIN
FOR bet IN
SELECT * FROM Carts WHERE CartID > startindex
LOOP
prices := ARRAY[]::INTEGER[];
FOR t IN
SELECT ItemID, Price FROM Prices WHERE ItemID = ANY(cart.Items)
LOOP
prices := prices || t.Price;
END LOOP;
RAISE NOTICE '%', prices;
END LOOP;
END;
$function$
所以,我坚持新的价格阵列创建。价格的位置应与数组中的项目的位置相关联。怎么做?或者可能有更聪明的解决方案来节省价格?
答案 0 :(得分:1)
此查询选择resultObj(1).
AnlaysisType = 'multivariate'
GroupSolution = false
SignalType = 'distributed'
Processing = 'raw'
alpha = 10
crossvalidation = 1
dprime = 6.5811
bestLambda = []
bestBetas = []
scores = []
fitObj = []
,其价格来自表格carts
:
items
使用上述查询更新select cartid, array_agg(c.itemid) items, array_agg(i.price) prices
from (
select cartid, unnest(items) itemid
from carts
where cartid > 0 -- startindex
) c
join items i using(itemid)
group by 1
order by 1;
cartid | items | prices
--------+-----------+--------------
1 | {1,2,3} | {50,36,11}
2 | {4,5,6} | {22,54,38}
3 | {1,6,7,9} | {50,38,2,39}
(3 rows)
:
carts
如果必须保留数组元素的顺序,则查询必须更复杂一些。在聚合元素的阶段,使用row_number()的其他顺序。
update carts c
set items = n.items, prices = n.prices
from (
select cartid, array_agg(c.itemid) items, array_agg(i.price) prices
from (
select cartid, unnest(items) itemid
from carts
where cartid > 0 -- startindex
) c
join items i using(itemid)
group by 1
order by 1
) n
where n.cartid = c.cartid;