关于第二个问题. 您可以先在表中检查变量，然后再将其放入查询中.例如，您可以执行以下操作:

As for your second question. You can check your variable in your table before you put it inside your query. For example you can do this:

 String item1;

 if(table.getValueAt(i, 0) != null)
     item1 = table.getValueAt(i, 0);
 else
     item1 = null;

用"table.getValueAt(i，0)"替换item1并为"table.getValueAt(i，2)"创建一个item2

Replace item1 with you "table.getValueAt(i, 0)" and create an item2 for your "table.getValueAt(i,2)"

String sql1 = "INSERT INTO HREmpListofCard (EmpID, CardNbr, Status, Remarks) VALUES ("             
        +"'"+empID             
        +"','"+ITEM1
        +"','"+val             
        +"','"+ITEM2+"')";  

我还没有测试过，所以不确定它是否可以工作:)

I haven't tested this, so I'm not sure if it will work :)

祝你好运！