Re: Table Updates ..
От | Josh Berkus |
---|---|
Тема | Re: Table Updates .. |
Дата | |
Msg-id | 200303111957.23061.josh@agliodbs.com обсуждение исходный текст |
Ответ на | Table Updates .. (Rudi Starcevic <rudi@oasis.net.au>) |
Список | pgsql-sql |
Rudi, > If I have 3 tables : > > orders, > products, > orders_products ( join table for orders and products ) > > If I insert an order with two products I have: > > 2 rows in the products table, ( the two products ) > 1 row in the orders table and ( one order ) > 2 rows in the orders_products table. ( two products for this order ) > > So far so good. All that works well. > But what if next week one the the products in the products table is > updated and changed ? > Then my order from last week is now different -- corrupted. It links to > the same product_id but the product is changed. If you're concerned with "freezing" the product characteristics at the time of the order, the answer is to add all or most of the columns in the products table to orders_products. Then, at the time of order finalization (shipping? not sure) you copy those columns from products to order_products. If you're into ORDMBS, you could even create orders_products as inheriting products. But this isnt' required. This will work better than a monthly log. -- -Josh BerkusAglio Database SolutionsSan Francisco
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