Go Premium for a chance to win a PS4. Enter to Win

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 2456
  • Last Modified:

How to skip null columns with oracle data reader

Hi experts,
the code below works but how do i get it to include null columns instead of through an exception
"Column contains NULL data"

thanks
public static void Main(string[] args)
        {


            OracleConnection con = new OracleConnection();
            con = new OracleConnection("Data Source=**; User ID=**;Password=**");
            OracleCommand cmd = new OracleCommand();
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Connection = con;

            cmd.CommandText = "HE_GETGRADES";
            cmd.Parameters.Add("grades_cursor", OracleDbType.RefCursor);
            cmd.Parameters["grades_cursor"].Direction = ParameterDirection.ReturnValue;
            cmd.Parameters.Add("vp_id", OracleDbType.Decimal).Value = 15000028435389;

            con.Open();
            OracleDataReader reader;
            reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                Console.WriteLine("\t{0}\t{1}", reader.GetName(0),
                    reader.GetName(1));

                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}", reader.GetString(0),
                        reader.GetString(1));
                }
                reader.NextResult();

                //if (reader.Read())

                //{
                //    //Console.WriteLine("My result is: " + reader.GetString(1));
                //    Console.WriteLine("{0}\t{1}", reader.GetString(0),
                //        reader.GetString(1));

                //    Console.ReadLine();

                //}
                //else
                //{
                //    Console.WriteLine("No Rows Found.");
                //    Console.ReadLine();
                //}
                con.Close();
                con.Dispose();
            }
        }
    }
}

Open in new window

0
SirReadAlot
Asked:
SirReadAlot
  • 7
  • 4
1 Solution
 
Guy Hengel [angelIII / a3]Billing EngineerCommented:
2 options:
* either change the procedure to return non-nulls only
* change the code to check each column if it's null, and react accordingly (aka use a replacement value)
0
 
slightwv (䄆 Netminder) Commented:
At the .Net code layer check out:
http://forums.oracle.com/forums/thread.jspa?threadID=598612

Convert.IsDBNull(dr[1]))
0
 
SirReadAlotAuthor Commented:
orry meant this, but it still give the same error

while (reader.Read() || (Convert.IsDBNull(reader[1])))
            {
                Console.WriteLine("\t{0}\t{1}", reader.GetName(0),
                    reader.GetName(1));

                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}", reader.GetString(0),
                        reader.GetString(1));
0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
slightwv (䄆 Netminder) Commented:
Why do you have two while loops?  You only need one.

I'll work on expanding my test from your previous question.  I'll post it soon.
0
 
slightwv (䄆 Netminder) Commented:
Here's what I came up with.  If there's still problems, please add/subtract to my test SQL so I can reproduce the error on my end.

Given the database objects:
-----------------------------------
drop table tab1 purge;
create table tab1(col1 number, someColumn varchar2(20), thirdColumn char(1));

insert into tab1 values(15000028435389,'Hello','Z');
insert into tab1 values(25000028435389,'World','Z');
insert into tab1 values(25000028435389,null,'Z');
commit;

create or replace function myFunc (inputID number)
return sys_refcursor
is
myresult sys_refcursor;
begin
open myresult for select * from tab1 where col1=inputID;

return myresult;
end;
/



using System;
using System.Data;

using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;

public class Bob
{

	public static void Main(string[] args)
	{


			OracleConnection con = new OracleConnection();

			con = new OracleConnection("User Id=bud;Password=bud;Data Source=bud");

			OracleCommand cmd = new OracleCommand();
			cmd.CommandType = CommandType.StoredProcedure;
			cmd.Connection = con;
			cmd.CommandText = " myFunc ";

			cmd.Parameters.Add("myResult", OracleDbType.RefCursor);

			cmd.Parameters["myResult"].Direction = ParameterDirection.ReturnValue;

			cmd.Parameters.Add("myInput", OracleDbType.Int64).Value = 25000028435389;

			con.Open();


      		OracleDataReader reader;
			bool haveRows = false;

	        reader = cmd.ExecuteReader();
	        
	        	while (reader.Read()) {
					Console.WriteLine("=========================");
					Console.WriteLine("Column1 has: " + (Convert.IsDBNull(reader.GetValue(0))?"null":reader.GetDecimal(0).ToString()));
					Console.WriteLine("Column2 has: " + (Convert.IsDBNull(reader.GetValue(1))?"null":reader.GetString(1)));
					Console.WriteLine("Column3 has: " + (Convert.IsDBNull(reader.GetValue(2))?"null":reader.GetString(2)));
					haveRows = true;
				}


				if(!haveRows) {
					Console.WriteLine("No Rows Found.");
				}

			con.Close();
			con.Dispose();

	}

}

Open in new window

0
 
SirReadAlotAuthor Commented:
ok  2sec
0
 
SirReadAlotAuthor Commented:
HI,

no errors with your sql,

but i received Specified cast is not valid. in line 1

            >>    Console.WriteLine("Column1 has: " + (Convert.IsDBNull(reader.GetValue(0)) ? "null" : reader.GetDecimal(0).ToString()));

thanks
0
 
SirReadAlotAuthor Commented:
DONE THIS

 Console.WriteLine("Column1 has: " + (Convert.IsDBNull(reader.GetValue(0)) ? "null" : reader.GetString(0).ToString()));
                Console.WriteLine("Column2 has: " + (Convert.IsDBNull(reader.GetValue(1)) ? "null" : reader.GetString(1).ToString()));
                Console.WriteLine("Column3 has: " + (Convert.IsDBNull(reader.GetValue(2)) ? "null" : reader.GetString(2).ToString())); >>ERRORS HERE so i will check thre datatype
                haveRows = true;
0
 
SirReadAlotAuthor Commented:
hi
Console.WriteLine("Column1 has: " + (Convert.IsDBNull(reader.GetValue(0)) ? "null" : reader.GetString(0).ToString()));
                Console.WriteLine("Column2 has: " + (Convert.IsDBNull(reader.GetValue(1)) ? "null" : reader.GetString(1).ToString()));
                Console.WriteLine("Column3 has: " + (Convert.IsDBNull(reader.GetValue(2)) ? "null" : reader.GetOracleDecimal(2).ToString()));

works now, so to view the rest of the colums I will have to keep adding
Console.WriteLine("Column1 has: " + (Convert.IsDBNull(reader.GetValue(0)) ? "null" : reader.GetString(0).ToString()));
                Console.WriteLine("Column2 has: " + (Convert.IsDBNull(reader.GetValue(1)) ? "null" : reader.GetString(1).ToString()));
                Console.WriteLine("Column3 has: " + (Convert.IsDBNull(reader.GetValue(2)) ? "null" : reader.GetOracleDecimal(2).ToString()));

right
0
 
slightwv (䄆 Netminder) Commented:
Correct.  You need to make sure the column offset is correct in the GetValue and Get<DataType> calls and the data types match.

So the next column would have offset (3).

Console.WriteLine("Column4 has: " + (Convert.IsDBNull(reader.GetValue(3)) ? "null" : reader.GetOracleDecimal(3).ToString()));

0
 
SirReadAlotAuthor Commented:
many thanks once again
0
 
SirReadAlotAuthor Commented:
what a cool teacher!!!
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

  • 7
  • 4
Tackle projects and never again get stuck behind a technical roadblock.
Join Now