Ошибка "Can't write CLR type System.String with handler type Int32Handler", что делать?

Question

[Grngr7]

При попытке выбрать данные из комбобокса (place) возникает ошибка "Can't write CLR type System.String with handler type Int32Handler". Проверил всё, не могу понять, в чём проблема. В базе у первичных ключей тип serial4, у вторичных - int4

Вот код:

private void PlaceLoad()
        {
            drschool_Data.command = new NpgsqlCommand("select place_name from places", drschool_Data.conn);

            drschool_Data.dataReader = drschool_Data.command.ExecuteReader();
            List<string> elems = new List<string>();

            while (drschool_Data.dataReader.Read())
            {
                elems.Add(drschool_Data.dataReader[0].ToString());
            }

            drschool_Data.dataReader.Close();

            place.ItemsSource = elems;
        }
        private void InstrAdd1_Click(object sender, RoutedEventArgs e)
        {
            if (instr_name.Text != "" && birth_date.Text != "" && exp.Text != "" && place.SelectedIndex != -1)
            {
                drschool_Data.trans = drschool_Data.conn.BeginTransaction();

                string selectedPlace = place.SelectedItem.ToString();
                drschool_Data.command = new NpgsqlCommand("select id_place from places where place_name = :value1", drschool_Data.conn);
                drschool_Data.command.Parameters.Add(new NpgsqlParameter(":value1", NpgsqlDbType.Varchar));
                drschool_Data.command.Parameters[0].Value = selectedPlace;
                int id_place = (int)drschool_Data.command.ExecuteScalar();
                try
                {
                    drschool_Data.command = new NpgsqlCommand("insert into instructors(snp_instr, birth_date_instr, experience, id_place) values(:value1, :value2, :value3, :value4)", drschool_Data.conn);
                    drschool_Data.command.Parameters.Add(new NpgsqlParameter("value1", NpgsqlDbType.Varchar));
                    drschool_Data.command.Parameters.Add(new NpgsqlParameter("value2", NpgsqlDbType.Varchar));
                    drschool_Data.command.Parameters.Add(new NpgsqlParameter("value3", NpgsqlDbType.Varchar));
                    drschool_Data.command.Parameters.Add(new NpgsqlParameter("value4", NpgsqlDbType.Integer));
                    drschool_Data.command.Parameters[0].Value = instr_name.Text;
                    drschool_Data.command.Parameters[1].Value = birth_date.Text;
                    drschool_Data.command.Parameters[2].Value = exp.Text;
                    drschool_Data.command.Parameters[3].Value = selectedPlace;
                    drschool_Data.command.ExecuteScalar();

                    drschool_Data.trans.Commit();
                    this.Close();
                }
                catch (Exception ex)
                {
                    drschool_Data.trans.Rollback();

                    MessageBox.Show(ex.Message);
                }

            }
        }

Буду очень рад, если поможете :(

Answer 1

[Станислав Макаров]

drschool_Data.command.Parameters.Add(new NpgsqlParameter("value4", NpgsqlDbType.Integer)); // тут Integer
...
string selectedPlace = place.SelectedItem.ToString();
drschool_Data.command.Parameters[3].Value = selectedPlace; // тут String
...

Comments

[Grngr7]

Понял, спасибо!