MySQL UPDATE ON DUPLICATE KEY仅插入

我正在尝试运行查询，以便它将重复插入或更新。我为重复项使用了唯一索引，但似乎无法正常工作。它仍然添加新记录。希望能有新的观点指出我的问题。谢谢。

这是我的图式

CREATE TABLE IF NOT EXISTS `pricing_puchasing` (
  `custno` varchar(6) DEFAULT NULL COMMENT 'customer code',
  `recipe` varchar(15) DEFAULT NULL,
  `item` varchar(120) NOT NULL COMMENT 'Item Code from dProduce',
  `unit_weight` double(12,4) DEFAULT NULL,
  `case_cost` double(12,4) DEFAULT NULL COMMENT 'Projected cost of item',
  `cost_per_lb` double(12,4) NOT NULL,
  `projected_price` float(12,3) DEFAULT NULL COMMENT 'projected Price',
  `projected_margin` float(12,3) DEFAULT NULL COMMENT 'Projected Margin',
  `trend` tinyint(1) DEFAULT NULL COMMENT 'Trend status 1=up, 0=down',
  `note` varchar(255) DEFAULT NULL COMMENT 'Note about the data',
  `week_of` date NOT NULL COMMENT 'Week of this data',
  `approved` tinyint(1) DEFAULT NULL COMMENT 'approval flag',
  `last_edited_from` varchar(20) NOT NULL COMMENT 'identifier to know where it was last saved from',
  `saved_at` datetime NOT NULL COMMENT 'Date time of save/update',
  `saved_by` int(11) NOT NULL COMMENT 'Created by user ID'
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Stores pricing purchasing data';


ALTER TABLE `pricing_puchasing`
 ADD UNIQUE KEY `custno_recipe_item_week_of` (`custno`,`recipe`,`item`,`week_of`), ADD KEY `custno` (`custno`);

这是我正在测试的查询：

INSERT INTO pricing_puchasing 
    (recipe,item,unit_weight,case_cost,cost_per_lb,trend,note,week_of,saved_at,saved_by,approved,last_edited_from) 
VALUES 
    ('APPLEGRRAW','APPLEGRRAW',40.00,100.01,2.50,0,'','2014-07-28',NOW(),1,NULL,'purchasing') 
ON DUPLICATE KEY UPDATE 
    unit_weight=40.00,case_cost=100.01,cost_per_lb=2.50,trend=0,note='',saved_at=NOW(),saved_by=1,approved=NULL,last_edited_from='purchasing'

编辑我解决了custno丢失的问题，但是我仍然对插入重复项有疑问。我创建了一个sqlfiddle。这次我正在测试2个NULL值，但还是不行...是我的架构还是我的查询问题？