I am trying to have a function that can search for an item (in this case, a motherboard) in a database when given parameters, but I want to be able to get all motherboards if no parameters are given.
The query is:
SELECT * FROM motherboard WHERE slot_type_cpu LIKE @cpu_slot AND hdd_num > @hdd_num AND sata_gen LIKE @sata_gen AND ram_pins LIKE @ram_pins AND ram_type LIKE @ram_gen AND ram_num > @ram_num AND gpu_num > @gpu_num AND gpu_slot LIKE @gpu_slot AND usb_num > @usb_num AND usb_gen LIKE @usb_gen;
Here is the current function:
public Motherboard[] getMBs(string cpu_slot = "%", string gpu_slot = "%", string hdd_gen = "%", string sata_gen = "%", string ram_gen = "%", string usb_gen = "%", int hdd_num = 0, int ram_pins = 0, int ram_num = 0, int gpu_num = 0, int usb_num = 0)
{
try
{
Motherboard[] mbList = new Motherboard[96];
Motherboard[] finishedList = new Motherboard[96];
MySqlConnection connect = new MySqlConnection(CONNECTION_STRING);
MySqlCommand useCmd = connect.CreateCommand();
MySqlCommand getMBCmd = connect.CreateCommand();
MySqlCommand getItemInfoCmd = connect.CreateCommand();
useCmd.CommandText = "use " + DEFAULT_DB + ";";
getMBCmd.CommandText = GET_MB_CMD;
getItemInfoCmd.CommandText = GET_ITEM_INFO_CMD;
connect.Open();
useCmd.ExecuteNonQuery();
getMBCmd.Parameters.AddWithValue("@cpu_slot", cpu_slot);
getMBCmd.Parameters.AddWithValue("@hdd_num", hdd_num);
getMBCmd.Parameters.AddWithValue("@sata_gen", sata_gen);
getMBCmd.Parameters.AddWithValue("@gpu_slot", gpu_slot);
getMBCmd.Parameters.AddWithValue("@hdd_gen", hdd_gen);
getMBCmd.Parameters.AddWithValue("@ram_gen", ram_gen);
getMBCmd.Parameters.AddWithValue("@usb_gen", usb_gen);
getMBCmd.Parameters.AddWithValue("@ram_pins", ram_pins);
getMBCmd.Parameters.AddWithValue("@ram_num", ram_num);
getMBCmd.Parameters.AddWithValue("@gpu_num", gpu_num);
getMBCmd.Parameters.AddWithValue("@usb_num", usb_num);
MySqlDataReader reader = getMBCmd.ExecuteReader();
reader.Read();
//Here comes the trouble part.
if (reader.HasRows)
{
int i = 0;
while (reader.HasRows)
{
mbList[i] = new Motherboard(reader.GetString(0), "", "", 0.00, 0, reader.GetString(1), reader.GetString(3), new RAM("", "", "", 0, 0, reader.GetString(5), reader.GetInt32(4), 0), reader.GetString(8), reader.GetInt32(2), reader.GetInt32(6), reader.GetInt32(7), reader.GetInt32(10), reader.GetInt32(11), reader.GetInt32(12));
i++;
reader.Read();
}
}
reader.Close();
//It doesn't retrieve any items, even though I can retrieve them manually using the same query...
int y = 0;
foreach (Motherboard m in mbList)
{
getItemInfoCmd.Parameters.AddWithValue("@id", m.id()); //This gives an Object reference not set to an instance of an object error
reader = getItemInfoCmd.ExecuteReader();
reader.Read();
if (reader.HasRows)
finishedList[y] = new Motherboard(m.id(), reader.GetString(3), reader.GetString(4), reader.GetDouble(1), reader.GetFloat(2), m.CPU_Slot(), m.HDD_Conn(), m.RAM(), m.GPU_Slot(), m.HDD_num(), m.RAM_num(), m.GPU_num(), m.USB_num(), m.USB_gen(), m.CPU_num());
reader.Close();
getItemInfoCmd.Parameters.Clear();
}
connect.Close();
return finishedList;
}
catch (Exception e)
{
Error error = new Error();
error.reportError(e.Message.ToString() + " " + e.StackTrace.ToString(), DateTime.Now.ToString(), "ItemRetrieval.getMBs: { } ");
return null;
}
EDIT: (HOW I FIXED IT)
What I ended up doing and it works fine (this might have been what aleroot meant, but I couldn’t deciper what they said… sorry.):
if (cpu_slot == "%")
getMBCmd.CommandText = getMBCmd.CommandText.Replace("@cpu_slot", "\'%\'");
else
getMBCmd.Parameters.AddWithValue("@cpu_slot", cpu_slot);
if(gpu_slot == "%")
getMBCmd.CommandText = getMBCmd.CommandText.Replace("@gpu_slot", "\'%\'");
else
getMBCmd.Parameters.AddWithValue("@gpu_slot", gpu_slot);
if(hdd_gen == "%")
getMBCmd.CommandText = getMBCmd.CommandText.Replace("@hdd_gen", "\'%\'");
else
getMBCmd.Parameters.AddWithValue("@hdd_gen", hdd_gen);
if(sata_gen == "%")
getMBCmd.CommandText = getMBCmd.CommandText.Replace("@sata_gen", "\'%\'");
else
getMBCmd.Parameters.AddWithValue("@sata_gen", sata_gen);
if (ram_gen == "%")
getMBCmd.CommandText = getMBCmd.CommandText.Replace("@ram_gen", "\'%\'");
else
getMBCmd.Parameters.AddWithValue("@ram_gen", ram_gen);
getMBCmd.Parameters.AddWithValue("@usb_gen", usb_gen);
getMBCmd.Parameters.AddWithValue("@hdd_num", hdd_num);
getMBCmd.Parameters.AddWithValue("@ram_pins", ram_pins);
getMBCmd.Parameters.AddWithValue("@ram_num", ram_num);
getMBCmd.Parameters.AddWithValue("@gpu_num", gpu_num);
getMBCmd.Parameters.AddWithValue("@usb_num", usb_num);
You can pass
%wildcard as a default parameter for the mainboard , so if you set as default%and filter with a like, in the case of missing mainboard parameter you will get all of your mainboard …