Добавить данные в базу данных

public string InsertContact(string contactName)
{
    contactName = contactName ?? "Unknown contact";
    var ins = new Insert(UserConnection)
        .Into("Contact")
        .Set("Name", Column.Parameter(contactName));
    var affectedRows = ins.Execute();
    var result = $"Inserted new contact with name '{contactName}'. {affectedRows} rows affected";
    return result;
}

public string InsertCity(string city, string country)
{
    city = city ?? "unknown city";
    country = country ?? "unknown country";

    var ins = new Insert(UserConnection)
        .Into("City")
        .Set("Name", Column.Parameter(city))
        .Set("CountryId",
            new Select(UserConnection)
                    .Top(1)
                    .Column("Id")
                .From("Country")
                .Where("Name")
                    .IsEqual(Column.Parameter(country)));
    var affectedRows = ins.Execute();
    var result = $"Inserted new city with name '{city}' located in '{country}'. {affectedRows} rows affected";
    return result;
}