Got Null result from Oracle even though the real result are decimal value - oracle

Question

I am new to Oracle in Visual Studio,
I used Oracle.ManagedDataAccess as my reference,
The case is whenever I tried to retrieve decimal value from arithmetic in Oracle query, Its always return null
e.g
SELECT 26/3 FROM DUAL < ---- This code return null in my visual studio but has a value in TOAD.
Did I do it wrong ?
Here is my code to retrieve the value
List<object[]> result = new List<object[]>();
OracleDataReader data;
string constr = ConfigurationManager.ConnectionStrings["OraConnection"].ConnectionString;
using (OracleConnection con = new OracleConnection(constr))
{
string query = QueryString;
using (OracleCommand cmd = new OracleCommand(query))
{
cmd.Connection = con;
con.Open();
data = cmd.ExecuteReader();
try
{
if (data.HasRows)
{
while (data.Read())
{
object[] itemData = new object[data.FieldCount];
//Dictionary<string, string> itemData = new Dictionary<string, string>();
for (int i = 0; i < data.FieldCount; i++)
{
Type type = data.GetValue(i).GetType();
if (typeof(string) == type)
{
itemData[i] = data.GetString(i);
}
if (typeof(DateTime) == type)
{
itemData[i] = data.GetDateTime(i);
}
if (typeof(int) == type)
{
itemData[i] = data.GetInt32(i);
}
if (typeof(decimal) == type)
{
itemData[i] = data.GetDecimal(i);
}
if (typeof(bool) == type)
{
itemData[i] = data.GetBoolean(i);
}
if (typeof(TimeSpan) == type)
{
itemData[i] = data.GetTimeSpan(i);
}
if (typeof(Single) == type)
{
itemData[i] = Convert.ToDecimal(data.GetOracleDecimal(i).ToString());
}
}
result.Add(itemData);
}
}
else
{
Console.WriteLine("Rows not found.");
}
}
finally
{
data.Close();
}
con.Close();
}
}
return result;
UPDATED : It got null just for division which has decimal value. Addition, Substraction, multiplication has no issue

Answer 1

It seems your data type doesn't match any of your if expressions. As there is no default branch, itemData[i] remains null. I suggest something like the following to find the gap:
for (int i = 0; i < data.FieldCount; i++)
{
Type type = data.GetValue(i).GetType();
switch(type)
{
case typeof(string):
itemData[i] = data.GetString(i);
break;
case typeof(DateTime):
itemData[i] = data.GetDateTime(i);
break;
case typeof(int):
itemData[i] = data.GetInt32(i);
break;
case typeof(decimal):
itemData[i] = data.GetDecimal(i);
break;
case typeof(bool):
itemData[i] = data.GetBoolean(i);
break;
case typeof(TimeSpan):
itemData[i] = data.GetTimeSpan(i);
break;
case typeof(Single):
itemData[i] = Convert.ToDecimal(data.GetOracleDecimal(i).ToString());
break;
default:
MessageBox.Show("Unknown type " + type.Name);
break;
}
}

Answer 2

So, I got an advice to edit the oracle query
From (e.g.)
SELECT 26/7 FROM DUAL
TO
SELECT TO_CHAR(26/7) FROM DUAL
And yes it works
But still, I don't know why