Solved

Cleaning up after using an OleDbDataReader

Posted on 2006-07-18
5
465 Views
Last Modified: 2012-06-27
Hi,

I have just been made aware that I need to call Dispose() when using an OleDbCommand.  I now do this in the "finally" block of the code to make sure it gets called when an exception is thrown.  But what about an OleDbDataReader?

Is this code appropriate?

OleDbDataReader driverRuns = dbSelectCommand1.ExecuteReader();             
driverRuns.Close();

If there is an exception in ExecuteReader(), does the Close() need to be called? I assume it's null anyway.  Then what about explicitly setting the OleDbDataReader to null?  This would be something I would also put into the finally block.

driverRuns = null;

Thanks,
Bob
0
Comment
Question by:ba272
  • 2
  • 2
5 Comments
 
LVL 18

Accepted Solution

by:
Ravi Singh earned 300 total points
ID: 17131827
Hi Bob, if all your database related code is within one try catch block then its always good to do a null check on the object in the finally clause (to avoid any runtime null reference exceptions)... if not null then close the reader and dispose it explicitly... this should mark it for garbage collection.

..
OleDbDataReader driverRuns = null;

try
{
     //...
     driverRuns = dbSelectCommand1.ExecuteReader();
     //... use the reader
}
catch (Exception ex)
{
}
finally
{
     if (driverRuns != null)
     {
          driverRuns.Close();
          driverRuns.Dispose();
     }
}
0
 
LVL 25

Assisted Solution

by:dstanley9
dstanley9 earned 200 total points
ID: 17131865
Easiest way to handle this is to use a using block:

using(OleDbDataReader driverRuns = dbSelectCommand1.ExecuteReader())
{
  while(driverRuns.Read())
  {
   
  }
}

This automatically disposes the OleDbDataReader (which closes it) in a finally block without having to explicitly close or dispose of the reader.  Using blocks can be used around Commands and Connections as well.
0
 

Author Comment

by:ba272
ID: 17131972
I will use the "using" statement in the future.  But I have hundreds of uses of these objects and need a quick way to make them as safe as possible, and to prevent memory leaks.

So I like Zephyr's approach for now.  Except I don't find a Dispose() in the OleDbDataReader object.

Am I missing something?

Bob
0
 
LVL 18

Expert Comment

by:Ravi Singh
ID: 17132113
Hi, sorry the data reader doesnt expose the Dipose() method... calling close on the reader should do it
0
 

Author Comment

by:ba272
ID: 17132560
Ok.  No problem.

Thanks.
0

Featured Post

Networking for the Cloud Era

Join Microsoft and Riverbed for a discussion and demonstration of enhancements to SteelConnect:
-One-click orchestration and cloud connectivity in Azure environments
-Tight integration of SD-WAN and WAN optimization capabilities
-Scalability and resiliency equal to a data center

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Summary: Persistence is the capability of an application to store the state of objects and recover it when necessary. This article compares the two common types of serialization in aspects of data access, readability, and runtime cost. A ready-to…
Exception Handling is in the core of any application that is able to dignify its name. In this article, I'll guide you through the process of writing a DRY (Don't Repeat Yourself) Exception Handling mechanism, using Aspect Oriented Programming.
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question