mysql (Basic opening page operation using database)

Hi everybody lots of thanks for your previous helps,

my question is about how to build a check "username/password". I cant figure out it.

String username = t1.getText();
String passwords = t2.getText();
Statement st;
Statement st2 = null;

try {
st = openConnection();
res = st.executeQuery("SELECT * FROM giris WHERE=" + username);
res2 = st2.executeQuery("SELECT * FROM giris WHERE=" + password);

} catch (Exception ex) {

JOptionPane.showConfirmDialog(null, "Bağlantı Başarısız", "MySQL Bağlantısı", JOptionPane.PLAIN_MESSAGE);
}

I want to build a classic username/password page. if username and password are true, then pass to rest part of the program.

Thanks in advance to everybody.

What's the structure of your table, can you show it here?

Basically what you have to do is, write a single query and check the combination of user name and the password. The you can check the effective number of rows, should be only one. Or else return the table index. It depends on the design you've.

Quote:

---

Originally Posted by Eranga

What's the structure of your table, can you show it here?

---

in my table, there are three rows and two columns at the beginning.However, row number will increase when users add new users.

if(!res.isFirst())
res.first();

do
{

if (t1.getText().equalsIgnoreCase(res.getString(1)) && t2.getText().equalsIgnoreCase(res.getString(2))) {

Anasayfa yeni = new Anasayfa();
giris eski = new giris();

yeni.setVisible(true);
dispose();
res.close();
}
}while(res.next());


if(!res.isClosed())
{
JOptionPane.showMessageDialog(null,"Kullanıcı Adı / Şifre Yanlış");
t1.setText("");
t2.setText("");
res.close();
}
} catch (SQLException ex) {
// Logger.getLogger(giris.class.getName()).log(Level. SEVERE, null, ex);
}


this is working now but I dont think so it is so reliable..:)

your corrections will be appreciated ..

Yes, by adding new users always the number of rows are increasing. Without that how you can added new users. But the point is two or more users cannot be there with the same user name. So always your query returns one entry.

So long as your user table has a unique key (in the form of the username in your case), you need just the single query (as already mentioned). That query will return either one row or none, so a check of

Code:

---

if (rs.next()) {
    // Successfully logged in!
}

---

will do.

If you find yourself getting data from a db and then iterating over the resultset to find a subset of what's returned then you have probably got the query wrong.

Thanks for your helps Eranga and Tolls..

with the help of your helps , I got where my problem is.. Previously, I tried to query a table and check that result set in my program. This causes a problem in which Username or Password is wrong message box .anyway.. Thanks .. :)

Adding more, in most of the designs successful queried returns a session key for the user, which use in the rest of the process.

If you've solve the problem, it's time to mark the thread solved.