mysql - 如何使用java将空值传递给mysql存储过程

Question

下面是我的存储过程

DROP PROCEDURE `addRecord`//
CREATE DEFINER=`root`@`localhost` PROCEDURE `addRecord`(company varchar(3000),name                 
varchar(3000),title varchar(3000),metro varchar(3000),city varchar(3000),email  
varchar(3000),phone varchar(3000),industry varchar(3000))

BEGIN

    insert ignore into record_data (company,name,title,metro,city,email,phone,industry)        
            values(company,name,title,metro,city,email,phone,industry);
END

我的主要任务是检查重复条目。如果我为所有字段提供一些值，它工作正常。但是，如果我从 java 提供某些字段为 null，它会插入一个新行。而不是消除重复。 例如

   if i use following statement it dosent insert an entry if it exists

   record.addRecord("abc", "a", "abc", "a","b","ostwal@gmail.com", "518- 220", "intl");

   but if use 
   record.addRecord("abc", "a", "abc", null,null,"ostwal@gmail.com", "518- 220", null);
   it inserts another row even if it already exists.