ResultSet

[Jenn Person]

Alright, I'm finishing up my login page. Users can login successfully, if they provide the wrong password they are notified, however if they enter a username that doesn't exist the servlet bombs.

My query is simple, I select all from my user table where the login ids match. So if there is no match, then obviously the loginID doesn't exist. How do I test for that though?

For example:
String query = "SELECT * from user where loginID = '"+login+"'";
ResultSet resultSet = statement.executeQuery(query);

now where do I go from here? would all the attributes I would have acquired from the query be null, and simply test to see if one if null??

[Sripathi Krishnamurthy]

user resultSet.next() as shown

  
ResultSet resultSet = statement.executeQuery(query);
while(resultSet.next())
{
//if it enters here, there must be "atleast" one row that has satisfied
//your query. else if it does not enter here, there are ro rows retrieved.
}

[ March 24, 2005: Message edited by: Bear Bibeault ]

[Jenn Person]

I already know about the while(resultSet.next()) and that it means there is some results of my query. I'm asking how I can test if there are no results... like if(resultSet==null) ??? I'm new to java and need some help here!! Thanks!

[Sripathi Krishnamurthy]

boolean resultExists=false;
ResultSet resultSet = statement.executeQuery(query);
while(resultSet.next())
{
resultExists=true;
//if it enters here, there must be "atleast" one row that has satisfied your query.
//else if it does not enter here, there are ro rows retrieved.
}
you can use the boolean variable in your code to write further logic if required...
this is the only way as I know that you can check whether the resultset has retrieved any rows or not.

Cheers
Sripathi
[ March 24, 2005: Message edited by: Sripathi ]

[Adeel Ansari]

Originally posted by Jenn Person:
I'm asking how I can test if there are no results... like if(resultSet==null) ???

ResultSet wouldn't be null, until and unless you assign it null explicitly.

[Dave Brown]

Don't you just need to do a ..

String sError = null;
String query = "SELECT * from user where loginID = '"+login+"'";
ResultSet resultSet = statement.executeQuery(query);

if (resultSet.next()) {
// check password is correct , set sError if its incorrect..

} else {
sError = "You dont exist !";
}

if (sError != null){
// go login page showing sError
} else {
// do whatever needs to be done after successfull login.
}