Removing DataRow From array but not the DataTable 1

[KoRUPT]

Here is the code I am talking about:

			MySQL con = new MySQL();
			DataTable dt = new DataTable( "TEST" );

			con.FillDataTable( "SELECT 1 AS ID, \"Name1\" AS Name;", ref dt, true );
			con.FillDataTable( "SELECT 2 AS ID, \"Name2\" AS Name;", ref dt, false );
			con.FillDataTable( "SELECT 3 AS ID, \"Name3\" AS Name;", ref dt, false );
			con.FillDataTable( "SELECT 4 AS ID, \"Name4\" AS Name;", ref dt, false );
			con.FillDataTable( "SELECT 5 AS ID, \"Name5\" AS Name;", ref dt, false );
			con.FillDataTable( "SELECT 6 AS ID, \"Name6\" AS Name;", ref dt, false );
			con.FillDataTable( "SELECT 7 AS ID, \"Name7\" AS Name;", ref dt, false );

			DataRow[] r = dt.Select( "ID=4" );
			r[0]["Name"] = "Test4";
			dt.AcceptChanges();
			r[0].Delete();
			dt.AcceptChanges();

At the line "r[0].Delete()" the row is question is deleted from the datatable "dt". What I want to happen is that the row is removed from the DataRow[] array, but NOT the DataTable. Thank you.

 

[KoRUPT]

(sorry if I am doing this wrong but I dont know how to edit my post)

I noticed that the code is mostly links to my own functions, so let me explain a breif bit. The MySQL class sets up a connection to the server and implements some container functions. The MySQL.FillDataTable function fills a datatable with whatever is selected; the last parameter indicates whether to clear the table of all entries or add a new entry (true = clear).

So the DataTable dt has 7 rows, 2 columns before the select statement.

 

[JCruz063]

KoRUPT,

[b]DataRow[] r[/b] = dt.Select( "ID=4" );
r[0]["Name"] = "Test4";
dt.AcceptChanges();
[b]r[0][/b].Delete();

Well, you're invoking the Delete method of the DataRow class and thus, you're deleting the row, not the array element, and since this array row is a reference type, it's deleted from the DataTable where it came from.

I don't know how to manipulate arrays very much as I don't use them frequently because I like the much easier-to-use ArrayList type which is some sort of array on steroids. ArrayList is like a dynamic array to and from which you add/remove elements at will. I would suggest that you use the ArrayList instead of Array to accomplish what you want.

Here's the code:

ArrayList rows = [blue]new[/blue] ArrayList();

[blue]foreach[/blue] (DataRow row [blue]in[/blue] dt.Select("ID=4"));
{
   [green]// Add row to arraylist object[/green]
   rows.Add(row);
}

[green]// Use the first row[/green]
DataRow r = [b](DataRow)[/b]rows[0];
r["Name"] = "Test4";
dt.AcceptChanges();

[green]// Delete first row from the arraylist[/green]
rows.RemoveAt(0);

ArrayList stores its elements as object and you have to cast them into the appropriate types before you use them. That's what the line [tt]DataRow r = (DataRow)rows[0][/tt] mean.

Hope this helps!

JC

_________________________________________________
To get the best response to a question, read faq222-2244.

 

[DaZZleD]

or you can do:

[copy] DataTable dtTemp = dt.Copy();
DataRow[] r = dtTemp.Select( "ID=4" );
r[0]["Name"] = "Test4";
dtTemp.AcceptChanges();
r[0].Delete();
dtTemp.AcceptChanges();[/copy]

and then use dtTemp for any other modifications or display.


--------------------------
"two wrongs don't make a right, but three lefts do" - the unknown sage

 

[JCruz063]

DaZZleD,
Your approach is much simpler and cleaner - Have a star!

JC

_________________________________________________
To get the best response to a question, read faq222-2244.

 

[KoRUPT]

Thank you JC and DaZZleD. I am trying both approaches now and trying to work on implementing them. There are still some things in both approaches that I have to work out. Firstly, DaZZleD's approach is clean and good, but the point of trying to remove the DataRow array and NOT delete them, was so I can have references to the original data rather than copies. I did not make that clear in my OP so I appologize. I am now testing JC's method to see if the performance is acceptable.

Thanks once again for your help. Cheers.