Java with SQL Login related

Question

Everything is perfect when I'm logging in. But when I enter an account that doesn't exist, a message dialog loops by the number of account there is in my database. I believe this is because I used while(rss.next()). Here is my code:

try {
    if(e.getSource()==loginButton){
        int count = 1;
        conn=DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=login_DB;integratedSecurity=true");
        st=conn.createStatement();
        rss=st.executeQuery("select * from tblLogin");
        while(rss.next()){
            String user = rss.getString(1);
            String pass = rss.getString(2);
            if(usernameTF.getText().equals(user)&&passwordTF.getText().equals(pass)){
                JOptionPane.showMessageDialog(null,"YEAAAA");
            }//if success

            else {
                JOptionPane.showMessageDialog(null,"Account doesn't exist! Please try again.");
            }
        }//while
    }//getsource loginButton

Why don't you use a WHERE clause to get just the candidate records (should be at most one, actually), instead of all of them? — Thilo
– Thilo, Commented May 25, 2015 at 13:00
I created a database which only has 1 table, and only has username and password. I know its pretty stupid hahaha but tbh, Im still practicing creating a connection between the two ^_^ — Juju
– Juju, Commented May 25, 2015 at 13:13

shA.t · Accepted Answer · 2015-05-26 09:21:07Z

1

Do something like this..

int flag = 0;
if(usernameTF.getText().equals(user) && passwordTF.getText().equals(pass))
{
    flag=1; // if found then, value change to 1 otherwise it will be 0
}

//Now, put below condition after while loop
if (flag==1) {
    JOptionPane.showMessageDialog(null,"YEAAAA");
}
else {
    JOptionPane.showMessageDialog(null,"Account doesn't exist! Please try again.");                
}

OR

As @Thilo suggested, you can use WHERE clause in your SELECT query.

edited May 26, 2015 at 9:21

shA.t

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answered May 25, 2015 at 13:02

Ravi

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3 Comments

Juju Over a year ago

Nice idea :D It actually worked! I'll update you if I a logic problem comes up XD

Thilo Over a year ago

Better use a boolean flag for this. And there are things like continue, break, return, too for flow control.

Ravi Over a year ago

@Thilo boolean could be better option. Yes, of course, we can use continue in else condition before dialog box code. But, in that case dialog box will never popup. :)

kxdan · Accepted Answer · 2015-05-25 13:08:07Z

1

Instead of selecting all from TblLogin, put a WHERE Clause in the query so it only pulls from the database Where that username is true, then (assuming you've made it so only one username per account) there will be a result returned if the username is present, you can then compare hashes or passwords depending on what you've used. Example :

String queryCriteria = "SELECT Username, Password FROM TblLogin WHERE Username = ? ";

 statement= connection.prepareStatement(queryCriteria );
  statement.setString(1,usernameEntered);
  resultSet = stmt.executeQuery();

answered May 25, 2015 at 13:08

kxdan

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Comments

CriPstian · Accepted Answer · 2015-05-25 13:06:14Z

0

You need to use a local variable like 'found' how I set it below. When you find your match, you print your message and mark found = true. After you exit your loop you check the value of found and print your error message if needed.

if(e.getSource()==loginButton){
        int count = 1;
        conn=DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=login_DB;integratedSecurity=true");
        st=conn.createStatement();
        rss=st.executeQuery("select * from tblLogin");
        boolean found = false;
        while(rss.next()){
        String user = rss.getString(1);
        String pass = rss.getString(2);
        if(usernameTF.getText().equals(user)&&passwordTF.getText().equals(pass)){
            JOptionPane.showMessageDialog(null,"YEAAAA");
            found = true;
        }//if success
        }//while
    if(found)
            JOptionPane.showMessageDialog(null,"Account doesn't exist! Please try again.");
}//getsource loginButton

answered May 25, 2015 at 13:06

CriPstian

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2 Comments

Juju Over a year ago

I somehow get your point but can you explain what 'if(found)' do? I'm new to that xD I mean its my first time seeing an if statement with that expression :D

CriPstian Over a year ago

The if(found) tests if found == true It tests if we found the specific account that we are looking for

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