java - sql中的计数函数

Question

account_id    current_balance  opening_date1             100              2012-03-012             100              2012-4-01 3             100              2013-03-1

now when I am running query in sql work bench it's fine

select count(acc.account_id) 
from daily_account acc 
where acc.opening_date < '2013-03-01'

但是当我在 NetBeans 中运行它时，它没有给出正确的输出。

select count(acc.account_id) 
from daily_account acc 
where acc.opening_date < '"+ new Date((Integer.parseInt(FromYearComboBox.getSelectedItem().toString())-1900),FromMonthComboBox.getSelectedIndex(),Integer.parseInt(FromDateComboBox.getSelectedItem().toString()))).toString()

谁能帮我看看为什么会发生这种情况？

编辑:

rs = st.executeQuery("select count(acc.account_id) from daily_account
acc where  acc.opening_date < '"+ new
Date((Integer.parseInt(FromYearComboBox.getSelectedItem().toString())-1900),FromMonthComboBox.getSelectedIndex(),(Integer.parseInt(FromDateComboBox.getSelectedItem().toString()))).toString()+"';");

rs.next();

tabledata[0][2]=rs.getString(1);

Edit :: It is giving me wrong answer ...it is counting all the account id...

Answer 1

最后似乎有一个额外的右大括号)，即toString())))。应该少一个，例如

select count(acc.account_id) from daily_account acc where acc.opening_date < '"+ new Date((Integer.parseInt(FromYearComboBox.getSelectedItem().toString())-1900),FromMonthComboBox.getSelectedIndex(),Integer.parseInt(FromDateComboBox.getSelectedItem().toString())).toString()+"'";

注意事项 这确实使查询字符串的维护变得复杂。尝试预先构建日期字符串，然后附加到查询中。

另一个注意事项: 带参数的 Date 构造函数已被弃用，而且似乎您确实不需要日期而是字符串。在这种情况下，为什么不写一些简单的东西，例如:

 String dateStr = 
      String.valueOf(Integer.parseInt(
                              FromYearComboBox.getSelectedItem().toString())-1900)
  + FromMonthComboBox.getSelectedIndex()
  +FromDateComboBox.getSelectedItem().toString();

String queryStr = "select count(acc.account_id) from daily_account acc "+
                  " where acc.opening_date < '"+ dateStr +"'";