private void button1_Click(object sender, EventArgs e) { lbError.Text = ""; string EmpID = txtEmpID.Text; string pass = txtPassword.Text; EmployeeDB db = new EmployeeDB(); string role = db.CheckLogin(EmpID, pass); if (role == "") { lbError.Text = "Sorry, this account is not exist!"; } else if (role == "admin") { this.Hide(); frmMaintainBooks frm = new frmMaintainBooks(); frm.ShowDialog(); } else if (role == "employee") { this.Hide(); Employee ee = new Employee() { EmpID = EmpID, EmpPassword = pass }; frmChangeAccount frm = new frmChangeAccount(ee); frm.ShowDialog(); } }