C#.Net & MySQL Database Login error how to fix

Question

Pro devs, I have a problem with my code in c#.net and I knew you can help me. the problem is in the Login code, every time I entered a value that is existed in the database it says "Username or password is incorrect" and when I entered a value that does not exist in the DB it says again "Username or password is incorrect" please help me thank you.

I have tried to edit the query and remove the open close in the asterisk but the output is the same.

public void checkLoginAccount()
    {
        frmMain frmLogin = new frmMain();
        con = new MySqlConnection();
        con.ConnectionString = "server=localhost;userid=root;password=alpine;port=3305;database=pos_db;pooling=false;SslMode=none";

        con.Open();
        string qry = "SELECT COUNT(*) FROM pos_db.tbllogin WHERE BINARY Username=@user AND BINARY Password=@pass";
        MySqlCommand cmd = new MySqlCommand(qry, con);
        cmd.Parameters.AddWithValue("@user", frmLogin.txtUsername.Text);
        cmd.Parameters.AddWithValue("@pass", frmLogin.txtPassword.Text);

        int count = Convert.ToInt32(cmd.ExecuteScalar());

        if (count != 0)
        {   
            MessageBox.Show("Welcome");
        }
        else
        {
            MessageBox.Show("Either username or password is incorrect!");
            return;
        }
        con.Close();
        con.Dispose();
    }

stackoverflow.com/questions/1054022/…

mjwills
– mjwills

2019-06-24 11:45:17 +00:00
Commented Jun 24, 2019 at 11:45 — mjwills
– mjwills, Commented Jun 24, 2019 at 11:45
What file is the checkLoginAccount method in?

mjwills
– mjwills

2019-06-24 11:47:59 +00:00
Commented Jun 24, 2019 at 11:47 — mjwills
– mjwills, Commented Jun 24, 2019 at 11:47
the checkLoginAccount method is from another class.

Mark Nartea
– Mark Nartea

2019-06-25 01:44:51 +00:00
Commented Jun 25, 2019 at 1:44 — Mark Nartea
– Mark Nartea, Commented Jun 25, 2019 at 1:44

Elias N · Accepted Answer · 2019-06-24 11:31:28Z

4

You are creating a new form instance in your function:

 frmMain frmLogin = new frmMain();

So the username and password are always empty here:

cmd.Parameters.AddWithValue("@user", frmLogin.txtUsername.Text);
cmd.Parameters.AddWithValue("@pass", frmLogin.txtPassword.Text);

You need to use the right instance of your form.

answered Jun 24, 2019 at 11:31

Elias N

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3 Comments

xdtTransform Over a year ago

Basic debugging checking the variable value. Good catch.

Mark Nartea Over a year ago

Elias N What do you mean I need to use the right instance of my form?

Mark Nartea Over a year ago

I remove the new form instance "frmMain frmLogin = new frmMain" and use the original name of my form and I get a syntax error shows "An object reference is required for the non-static field, method, or property".

umair qayyum · Accepted Answer · 2019-06-24 11:42:44Z

-1

Try reading the rows and count in the code. That should look something like this:

string qry = "SELECT Username FROM pos_db.tbllogin WHERE BINARY Username=@user AND BINARY Password=@pass";
        MySqlCommand cmd = new MySqlCommand(qry, con);
        cmd.Parameters.AddWithValue("@user", frmLogin.txtUsername.Text);
        cmd.Parameters.AddWithValue("@pass", frmLogin.txtPassword.Text);

        mySqlDataReader reader = cmd.ExecuteReader();
        if(reader.Read() == true)
        {
            MessageBox.Show("Welcome");
        }
        else
        {
            MessageBox.Show("Either username or password is incorrect!");
            return;
        }

answered Jun 24, 2019 at 11:42

umair qayyum

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