Getting empty dataset in function which is called from thread or timer

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1.00/5 (1 vote)

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VS2010

Hello.
I am developing application with C#.net and sql DB, i am using dataset and adapters for data retrieve. I get dataset as empty if i run in timer or thread but if i run same query in sql server it give me some count of rows. When i run this code outside timer(on page lode or on button click) then it give me expected results
Issue with timer or thread.
I don't know why this is happening.

here 'ds' in empty in below code
tools : vs10, sqlserver 2008 R2

What I have tried:

private void timer_Tick(object sender, EventArgs e)
   {
       SqlConnection con = new SqlConnection("Integrated security=false;Initial Catalog=" + Catalog + ";Data source=" + DataSource + ";User ID=" + DBUserID + ";Password=" + DBPassword + "");
       string sSql = "SELECT * from table ";
       DataSet ds = new DataSet();
       SqlDataAdapter adap = new SqlDataAdapter(sSql, con);
       adap.Fill(ds);
       if (ds.Tables[0].Rows.Count > 0)
       {
       }
   }

Posted 29-Mar-19 3:40am

Nitin Surya

Updated 29-Mar-19 3:55am

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Richard MacCutchan · Answer 1 · 2019-03-29T03:55:00

Solution 1

The test for rows count does not actually do anything; how do you know it returns zero? Also, you are creating a new DatasSet and SqlDataAdapter inside the timer_Tick method. So as soon as that method returns, both objects go out of scope and disappear. Why are you using a timer in the first place?

Posted 29-Mar-19 3:55am

Richard MacCutchan

Comments

Nitin Surya 29-Mar-19 13:12pm

The test for rows count does not actually do anything; how do you know it returns zero? : i have not posted the code which is supposed to be done after rowcount > 0 for the sake of simplicity in question, i have just posted the code where i am getting issue...
i am checking in debug mode.

Also, you are creating a new DatasSet and SqlDataAdapter inside the timer_Tick method : yes.. here i will perform one task which is supposed to be performed on regular intervals... so this DataSet and SqlDataAdapter will not be used outside any where in project..

Richard MacCutchan 29-Mar-19 13:54pm

None of which tells us what results you get in these instances. You need to use your debugger to see what is happening. Do you really need to extract all records each time?

Nitin Surya 2-Apr-19 7:09am

yes