BalusC的答案是对的！但我必须根据用户实例变量提及，例如：

BalusC's answer is right! but I have to mention according to the user instance variable such as:

rSet.last(); 
total = rSet.getRow();

然后你缺少

rSet.beforeFirst();

剩下的代码是相同的，你会得到你想要的结果。

the remaining code is same you will get your desire result.