/// <summary>Gets the car statistics group by category.</summary>
/// <returns>The list of car statistics.</returns>
public List <CarStatistic> GetCarStatistics()
{
List <CarStatistic> carStatistics = new List <CarStatistic>();
var cmd = new NpgsqlCommand();
cmd.Connection = npgsqlConnection;
cmd.CommandText = "SELECT carcategory, count(*), avg(carmaxpower), "
+ "avg(carmaxspeed), avg(caracceleration), avg(carbraking), avg(carcornering), avg(carstability), avg(carprice) FROM cars "
+ "GROUP BY carcategory ORDER BY carcategory";
cmd.Prepare();
NpgsqlDataReader dataReader = cmd.ExecuteReader();
while (dataReader.Read())
{
CarStatistic carStatistic = RecordToStatistic(dataReader);
carStatistics.Add(carStatistic);
}
dataReader.Close();
cmd.Dispose();
return(carStatistics);
}
private CarStatistic RecordToStatistic(NpgsqlDataReader dataReader)
{
CarStatistic carStatistic = new CarStatistic();
carStatistic.Category = CarCategory.GetCategoryByDBValue(dataReader.GetString(0));
carStatistic.NumberOfCars = dataReader.GetInt32(1);
carStatistic.AvgMaxPower = dataReader.GetDouble(2);
carStatistic.AvgMaxSpeed = dataReader.GetDouble(3);
carStatistic.AvgAcceleration = dataReader.GetDouble(4);
carStatistic.AvgBraking = dataReader.GetDouble(5);
carStatistic.AvgCornering = dataReader.GetDouble(6);
carStatistic.AvgStability = dataReader.GetDouble(7);
carStatistic.AvgPrice = dataReader.GetDouble(8);
return(carStatistic);
}