Right way to use "using" on my code

Question

I just want to know if I did the right way in using the "using" in my CRUDStudentTable().

private string Query;
public string message;

public CRUD(string myQuery)
{
   Query = myQuery;
}

public void CRUDStudentTable()
    {
            using (OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Documents and Settings\Microsoft User\Desktop\Student.accdb"))
            {
                try
                {
                    conn.Open();
                    using (OleDbCommand cmd = new OleDbCommand(Query, conn))
                    {
                        cmd.ExecuteNonQuery();
                    }
                }
                catch (Exception exception)
                {
                    message = exception.Message;
                }
                finally
                {
                    conn.Close();
                }
            }
    }

public string HasError()
    {
        if (string.IsNullOrEmpty(message))
        {
            message = "Successful";
            return message;
        }
        else
        {
            return message;
        }
    }

If this is not right, kindly give me an advice on how to do this right. Thank you.

I included here another method that return the "message" whenever it is not null.

Get rid of the entire try block.

SLaks
– SLaks

2013-11-24 03:10:06 +00:00
Commented Nov 24, 2013 at 3:10 — SLaks
– SLaks, Commented Nov 24, 2013 at 3:10
I used the try block to catch errors.

noviceKid
– noviceKid

2013-11-24 03:11:45 +00:00
Commented Nov 24, 2013 at 3:11 — noviceKid
– noviceKid, Commented Nov 24, 2013 at 3:11

Sergey Kalinichenko · Accepted Answer · 2013-11-24 03:11:37Z

5

This is a kind of "belt and suspenders" approach: you should use either a using or a finally, but not both.

The using block guarantees to close your connection in all code paths, including the ones with exceptions. Therefore you can rewrite the code as follows:

public void CRUDStudentTable()
{
        using (OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Documents and Settings\Microsoft User\Desktop\Student.accdb"))
        {
            try
            {
                conn.Open();
                using (OleDbCommand cmd = new OleDbCommand(Query, conn))
                {
                    cmd.ExecuteNonQuery();
                }
            }
            catch (Exception exception)
            {
                message = exception.Message;
                // Consider re-throwing the exception here
                // to let callers know what happened.
                // Silently harvesting the message and continuing
                // is not a good practice of handling exceptions.
            }
        }
}

answered Nov 24, 2013 at 3:11

Sergey Kalinichenko

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7 Comments

zerkms Over a year ago

Probably it would also worth mentioning that catch (Exception exception) { message = exception.Message; } would be considered as a bad practice

Scott Chamberlain Over a year ago

@zerkms not necessarily, it all depends on what happens with message. I have done similar in WCF situations where allowing a exception to bubble up would fault the WCF channel when I have other ways of reporting the error without faulting the channel.

zerkms Over a year ago

@Scott Chamberlain: I didn't propose it to bubble up to the very top and get an unhandled exception, but it shouldn't be silently writing an exception message into an object's property without return false; or something like that to indicate it failed

zerkms Over a year ago

@user3026391: and how would you know if an error even occurred? Your method returns void, how would you know the result of the query execution?

noviceKid Over a year ago

@zerkms I edited my post. It shows there what I did with the "message". If I also did it the wrong way, please correct me.

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