کد رو تغییر دادم ولی همون ارور رو میده:database.Connection.Open();
var transaction = database.Connection.BeginTransaction();
try
{
DatabaseModel.tbl_Person psn = new DatabaseModel.tbl_Person()
{
firstName = txtName.Text.Trim(),
lastName = txtFamily.Text.Trim(),
nationalNumber = int.Parse(txtNationalID.Text.Trim())
};
database.tbl_Persons.InsertOnSubmit(psn);
database.SubmitChanges();
transaction.Commit();
}
catch (Exception exp)
{
MessageBox.Show(exp.Message);
transaction.Rollback();
}
database.Connection.Close();