VbzCart/tables/stk items

About

 * Purpose: listing of what is now and what used to be in stock
 * Refers to: ,
 * Notes: In early versions of VbzCart, this table was partly used as a sort of klugey stock-log. If a row containing qty>1 had less than qty removed from it, a new row was "split off" from the existing row and then the WhenRemoved timestamp was set, rather than setting qty to 0.
 * Fields:
 * WhenRemoved: DEPRECATED. Keep setting it properly until it is removed completely, but don't use it.
 * There are currently still a lot of records where WhenRemoved is set but Qty is > 0, so until that remediation has been done, we have to keep referring to WhenRemoved. For now, make sure that Qty is set to 0 whenever all pieces have been removed from a record.
 * Future: For all existing data where WhenRemoved is set and Qty>0, create stock log entries showing the removal and set Qty to 0. Finally, remove the WhenRemoved field altogether. Code which uses WhenRemoved as a flag should check the Qty field instead ("WhenRemoved IS NULL" -> "Qty > 0", "WhenRemoved IS NOT NULL" -> "Qty == 0").

SQL
DROP TABLE IF EXISTS `stk_items`; CREATE TABLE `stk_items` ( `ID` INT  NOT NULL AUTO_INCREMENT,  `ID_Bin` INT DEFAULT NULL COMMENT 'stk_bins.ID: which bin these items are in',  `ID_Item` INT DEFAULT NULL COMMENT 'cat_items.ID: which exact type of item',  `Qty` INT DEFAULT NULL,  `WhenAdded` DATETIME DEFAULT NULL COMMENT 'when stock record was created for this item',  `WhenChanged` DATETIME DEFAULT NULL COMMENT "when the quantity for this record was last altered (e.g. stock rmvd, or a split)",  `WhenCounted` DATETIME DEFAULT NULL COMMENT "when this stock record was last verified by hand-count",  `WhenRemoved` DATETIME DEFAULT NULL COMMENT "if not NULL, item is no longer in stock",  `Cost` INT DEFAULT NULL COMMENT "what we paid (each) for these particular items in stock",  `CatNum` varchar(63) DEFAULT NULL COMMENT "catalog number on tag (official cat# can change over time)",   `Notes` TEXT,   PRIMARY KEY(`ID`) ) ENGINE = MYISAM;