private void button2_Click_1(object sender, EventArgs e) { ClassDB db = new ClassDB(); String username = uname.Text; String password = pass.Text; DataTable table = new DataTable(); MySqlDataAdapter adapter = new MySqlDataAdapter(); MySqlCommand command = new MySqlCommand("SELECT * FROM admin WHERE username = @uname and password= @pass", db.getConnection()); command.Parameters.Add("@uname", MySqlDbType.VarChar).Value = username; command.Parameters.Add("@pass", MySqlDbType.VarChar).Value = password; adapter.SelectCommand = command; adapter.Fill(table); // check if the user exists or not if (table.Rows.Count > 0) { MessageBox.Show("Login Berhasil", "Selamat Datang", MessageBoxButtons.OK, MessageBoxIcon.Information); this.Hide(); DataPendaftaran datapendaftaran = new DataPendaftaran(); datapendaftaran.Show(); } else { // check if the username field is empty if (username.Trim().Equals("")) { MessageBox.Show("Enter Your Username To Login", "Empty Username", MessageBoxButtons.OK, MessageBoxIcon.Error); } // check if the password field is empty else if (password.Trim().Equals("")) { MessageBox.Show("Enter Your password To Login", "Empty password", MessageBoxButtons.OK, MessageBoxIcon.Error); } // check if the username or the password don't exist else { MessageBox.Show("Wrong username or password", "Wrong Data", MessageBoxButtons.OK, MessageBoxIcon.Error); } } }
public Boolean checkUsername() { ClassDB db = new ClassDB(); String username = tbUsername.Text; DataTable table = new DataTable(); MySqlDataAdapter adapter = new MySqlDataAdapter(); MySqlCommand command = new MySqlCommand("SELECT * FROM admin WHERE username = @usn", db.getConnection()); command.Parameters.Add("@usn", MySqlDbType.VarChar).Value = username; adapter.SelectCommand = command; adapter.Fill(table); // check if this username already exists in the database if (table.Rows.Count > 0) { return(true); } else { return(false); } }