private void btnAdd_Click(object sender, EventArgs e) { if (IsValidate()) { AdminsModel newAdmin = new AdminsModel() { Name = txtAdminName.Text, Password = txtAdminPassWord.Text }; List <AdminsModel> admins = PrepAndPaintDB.GetAdmins(); foreach (var name in admins) { if (name.Name == newAdmin.Name) { MessageBox.Show($"Name: {newAdmin.Name} already exist", "Exist Already!", MessageBoxButtons.OK, MessageBoxIcon.Error); txtAdminName.Focus(); return; } } PrepAndPaintDB.AddAdmin(newAdmin); txtAdminName.Clear(); txtAdminPassWord.Clear(); PopulateDataGrid(); } }