VbzCart/tables/shop cart

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[edit] About

• Purpose: Shopping cart data is kept separate from order data because we end up with a lot of carts that never become orders; eventually they get cleaned out. Order data may eventually get cleaned out too, but with different criteria; for now, we are keeping order data indefinitely.
• Relations:
  • each shop_cart has zero or one core_orders record (it's only zero until the order is placed)
  • each core_orders record has exactly one shop_cart
  • each shop_cart has zero or one core_custs record (it's only zero until the order is placed, but ID_Cust isn't necessarily filled in when this happens)
  • each core_custs record has one or more shop_carts and one or more core_orders
• Fields:
  • ID_Cust is for future use when customers can log in to retrieve their personal data before checking out
  • ID_Sess is the ID of the session (shop_session) where the cart was created & accessed
    • Different sessions cannot access the same cart. (Is there a good reason for this, or does it just sound good?)
    • One session may have multiple carts.
  • ShipZone represents the string-code for the shipping zone, which is used to determine shipping cost
    • currently, this is hard-coded to apply a different multiplier for each zone - {US shipping cost}x{zone multiplier}
• History:
  • 2009-06-16 Changing names to singular (tables not in use yet, so this is the time to do it)
  • 2009-07-10 removing ID_Session: each session ties to a cart, not vice-versa
  • 2009-07-16 added ShipZone field
  • 2009-07-18 added ID_Sess field (field documentation seems to think it was already there...)

[edit] SQL

DROP TABLE IF EXISTS `shop_cart`;
CREATE TABLE `shop_cart` (
  `ID`          INT            NOT NULL AUTO_INCREMENT,
  `WhenCreated` DATETIME       NOT NULL COMMENT "when the cart was first created",
  `WhenViewed`  DATETIME   DEFAULT NULL COMMENT "when the cart's contents were last displayed by the customer",
  `WhenUpdated` DATETIME   DEFAULT NULL COMMENT "when the cart's contents were last changed",
  `WhenOrdered` DATETIME   DEFAULT NULL COMMENT "when the cart's contents were transferred to an order",
  `ID_Sess`     INT            NOT NULL COMMENT "shop_session.ID which used this cart",
  `ID_Order`    INT        DEFAULT NULL COMMENT "core_orders.ID of order into which cart was transferred",
  `ID_Cust`     INT        DEFAULT NULL COMMENT "core_custs.ID of customer for this order",
  `ShipZone`    VARCHAR(3) DEFAULT NULL COMMENT "shipping cost zone",
   PRIMARY KEY(`ID`)
 ) ENGINE = MYISAM;