求一个很简单的问题!

[qianjing1111]

<%
java.sql.Connection con = null;
java.sql.ResultSet rs = null;
com.db.database.DatabaseObject dbBean = new com.db.database.DatabaseObject();
String question = "";
try{
dbBean.getConnection();
rs = dbBean.getResultSet(
"select usertable.userid,usertable.question from usertable where username='"+input+"'");
rs.next();
request.getSession().putValue("userid", rs.getString("userid"));
question = rs.getString("question");
if (question.equals("null"))
{


%>
<font color="#ff3333">该用户名不存在</font>
<%

}
else
{
}
%>
我现在想在if判断中显示一句"该用户名不存在" 应该怎么写啊?

[lun2001]

<%
java.sql.Connection con = null;
java.sql.ResultSet rs = null;
com.db.database.DatabaseObject dbBean = new com.db.database.DatabaseObject();
String question = "";
try{
dbBean.getConnection();
rs = dbBean.getResultSet(
"select usertable.userid,usertable.question from usertable where username='"+input+"'");
if(rs.next())
{
request.getSession().putValue("userid", rs.getString("userid"));
question = rs.getString("question");
}
else
{
%>
<font color="#ff3333">该用户名不存在</font>
<%
}
%>

[walkfish]

if (question==null || question.trim().equals("")
|| question.toLowerCase().equals("null")) {
%>
<font color="#ff3333">该用户名不存在</font>
<%
}

[qianjing1111]

<font color="#ff3333">该用户名不存在</font>

这句还是显示不出来 啊。。

[qianjing1111]

UP

[xylll]

首先要指出，rs集里只会存放数据库里有的记录，也就是存放与你表单提交的userid一致的那条记录，那么什么equals("null")之内的东西是不存在的，
只要用if(rs.next){}
else{out.println("用户名不存在");}