Oracle database "Specified cast is farmland valid"

This error occurs when the author performs a calculation of the number of rows that match the criteria, and reads the computed rows with OracleDataReader.

The query statements are:

Select Count (1) from Hp_ts  Where  ts_id>0

The C # execution process is:

public static int Getsingle (string strSQL)        {            try            {                openconnection ();                OracleDataReader Oradatareader = ExecuteReader (Connection, CommandType.Text, strSQL, null);                int count =-1;
                if (oradatareader.hasrows = = True && oradatareader.read ())                {                    count = oradatareader.getint32 (0);  ① This error exception is thrown here                }
                Oradatareader.close ();                return count;            }            catch (System.Exception ex)            {                throw ex;            }        }

Later debugging was found to be due to oradatareader[0] (or oradatareader["Count (1)"]), the type is decimal, so directly with the above code ① results, the exception described in this article will occur.

Later, the following workaround is given:

Replace the ① with the code shown below

Count = Convert.ToInt32 (oradatareader[0]. ToString ());

Oracle database "Specified cast is farmland valid"