Now lets write an update. Working pretty much like insert - but still it's here as a convienience and reference:
public void UpdateMySql(string newcity, int city_id)
{
MySql.Data.MySqlClient.MySqlConnection oConn =
new MySql.Data.MySqlClient.MySqlConnection("Database=sakila;Data Source=192.168.10.4;User id=stefan;Password=pekka");
oConn.Open();
MySql.Data.MySqlClient.MySqlCommand command =
new MySql.Data.MySqlClient.MySqlCommand("update city set city=?city where city_id=?city_id", oConn);
command.Parameters.Add(new MySql.Data.MySqlClient.MySqlParameter("?city", MySql.Data.MySqlClient.MySqlDbType.VarChar, 50));
command.Parameters.Add(new MySql.Data.MySqlClient.MySqlParameter("?city_id", MySql.Data.MySqlClient.MySqlDbType.Int64));
command.Parameters[0].Value = newcity;
command.Parameters[1].Value = city_id;
command.ExecuteNonQuery();
oConn.Close();
}