public void fillComboboxLocationNameWithSalaryNull(ComboBox comboBox)
{
comboBox.Items.Clear();
locationDB = new LocationDB();
connection = new DBConnection();
SqlDataReader reader = locationDB.fillComboboxLocationNameWithoutSalaryNull();
while (reader.Read())
{
comboBox.Items.Add(reader["name"]);
}
connection.close();
}