Re: Datasets - performing selects - C# Discussion Boards

18-Jun-03 3:13

is it possible to carry out SQL format selects directly onto datasets?

For example lets say I have a dataset with the following format :

<br />
      col1  col2  col3  col4<br />
row1  a     b     c     d<br />
row2  e     f     g     h<br />
row3  i     j     k     l<br />

Is there a way to run the following SQL command :

dsResult = SELECT col2, col3, col4 FROM dsSource.Tables[0] WHERE col1 = 'a'

Which would return the following into dsResult

<br />
col2  col3  col4<br />
b     c     d<br />

Oleksandr Kucherenko18-Jun-03 3:21

18-Jun-03 3:21

<br />
DataRow row = dsSource.Tables[0].Rows.Find( new object[] {'a'} );<br />

Good Luck
Alex Kucherenko

MrEyes18-Jun-03 3:35

18-Jun-03 3:35

Unfortunatly I probably over simplified things, so although the code you posted works perfectly it wont work in my code.

This is the scenario I am up agaisnt. I have a populated dataset with a single table, multiple rows, and multiple columns.

I need to add a column to this dataset but it has to be at position 7 (of 40), i.e. not at the end as columns.Add() would do.

The reason for asking about the possibilites of using selects is that the only way I can imagine doing this is to :

1) foreach through each row in the source dataset
2) Select all the data into a comma seperated string.
3) Inserting the new column (techincally another '',) where needed.
4) Build a new datarow from the string.
5) Insert the new datarow into another dataset

This all seems way to over complex for what originally seemed like a simple problem. I am sure I am missing something here put I cant put my finger on what it is.

Dimitris Iliopoulos18-Jun-03 5:10

Dimitris Iliopoulos

18-Jun-03 5:10

why do want the col in a specified position? you can create a Dataview but i don't think this is the best solution .If you want to show your data in a datagrid you can create a Tablestyle with specified columnstyles for this grid, so you can put the cols in specified positions look this piece of code:

System.Windows.Forms.DataGridTableStyle tempstyle=new System.Windows.Forms.DataGridTableStyle();

tempstyle.AllowSorting=true;
tempstyle.GridLineStyle=System.Windows.Forms.DataGridLineStyle.Solid;
tempstyle.MappingName=[tablename];

System.Windows.Forms.DataGridColumnStyle tempcol;

tempcol=new System.Windows.Forms.DataGridTextBoxColumn();

tempcol.HeaderText="Κωδικός";
tempcol.MappingName=[fieldname];
tempcol.NullText="";
tempcol.Width=50;
tempstyle.GridColumnStyles.Add(tempcol);

In this way add the columns you want in the position you like.

From Greece:
Dimitris Iliopoulos
dimilio@yahoo.com

Oleksandr Kucherenko18-Jun-03 3:26

Datasets - Adding columns

18-Jun-03 3:26

<br />
DataView view = new DataView( dsSource.Tables[0], "col1 = " + ... Value ..., "", DataViewRowState.CurrentRows );<br />

Good Luck
Alex Kucherenko

MrEyes18-Jun-03 2:03

18-Jun-03 2:03

Lets say I have a Dataset which contains one table, multiple datarows, and multiple populated datacolumns.

I want to add another column to this dataset BUT I need to add it at a specific postion. For example there are 20 datacolumns and I want to insert a column at position 7 (shuffling all the others up)

I have been looking at Columns.Add() but I cant find any functionality to allow me to specify postion as this seems to just add the new column to the end of the datarow.

Does anybody know of a way of doing this, without disassembling the dataset and rebuilding with the new column.

Oleksandr Kucherenko18-Jun-03 3:36

18-Jun-03 3:36

<br />
DataSet dsSet;<br />
DataTable table;<br />
<br />
// ... fill of dataset ...<br />
<br />
DataColumn[] columns = new DataColumn[ table.Columns.Count ];<br />
table.Columns.CopyTo( columns, 0 );<br />
<br />
// ... <br />
table.Columns.Clear(); <br />
<br />
ArrayList lst = new ArrayList( columns );<br />
<br />
// change order and quantity of columns <br />
lst.Insert( ... );<br />
lst.RemoveAt( ... );<br />
lst.Add( ... );<br />
<br />
// add columns to table again<br />
table.Columns.AddRange( ( DataColumn[] )lst.ToArray( typeof( DataColumn ) ) );<br />
<br />
lst.Clear();<br />

Only one note... I don't know what will happens with DataTable Data...

Good Luck
Alex Kucherenko

MrEyes18-Jun-03 4:17

18-Jun-03 4:17

That works brilliantly but as you mentioned there is a problem with the data, it isnt carried across into the dataset.

The code I am using at the moment is this :

<br />
//get all columns in dsSource to arraylist<br />
DataColumn[] columns = new DataColumn[ dsSource.Tables[0].Columns.Count ];<br />
dsSource.Tables[0].Columns.CopyTo( columns, 0 );<br />
ArrayList lst = new ArrayList( columns );<br />
dsSource.Tables[0].Columns.Clear();<br />
<br />
//insert new column<br />
DataColumn dc = new DataColumn();<br />
lst.Insert(7, dc);<br />
<br />
// add columns to dsNew<br />
dsSource.Tables[0].Columns.AddRange( ( DataColumn[] )lst.ToArray( typeof( DataColumn ) ) );<br />
<br />
lst.Clear();<br />

Currently working on getting the data across

Oleksandr Kucherenko18-Jun-03 4:43

18-Jun-03 4:43

Try such way:
- create copy of DataColumns
- change in copy name to unique one (add prefix to names)
- add copy DataColumns to collection
- ??? map data of old columns to new columns ??? (how to do that???)
- remove old columns from collection
- change names of columns to default one (remove prefix from names)

I don't know how to re-map columns data, but i think this is easier to do then copy all data from dataset...

Good Luck
Alex Kucherenko

MrEyes18-Jun-03 4:50

18-Jun-03 4:50

I am currently working on a variation of the code you posted earlier.

Rather than working with columns I am working with the datarows as these seem to maintain the data within them

this is the code I have at the moment

<br />
DataRow[] rows = new DataRow[ dsSource.Tables[0].Rows.Count ];<br />
dsSource.Tables[0].Rows.CopyTo(rows, 0);<br />
ArrayList lst = new ArrayList( rows);<br />
DataSet dsNew = new DataSet();<br />
<br />
foreach(DataRow drs in lst)<br />
{<br />
	ArrayList lst2 = new ArrayList(drs.ItemArray);<br />
	lst2.Insert(3, "Insert Value");<br />
	DataRow ndr = dsNew.Tables[0].NewRow();<br />
<br />
	//get data from lst2 into ndr????<br />
	//ndr.ItemArray = lst2;<br />
<br />
	dsNew.Tables[0].Rows.Add(ndr);<br />
}

My only problem is getting the arraylist of row values back into the new datarow, but I have only been stuck here for a few minutes, hopefully the solution will come to me soon

MrEyes18-Jun-03 5:21

18-Jun-03 5:21

Well here it is, this piece of code will take a dataset (dsSource) add a column and write the results into a second dataset (dsNew).

Its dirty, it aint pretty, but it does the job (ish)

<br />
DataRow[] rows = new DataRow[ dsSource.Tables[0].Rows.Count ];<br />
dsSource.Tables[0].Rows.CopyTo(rows, 0);<br />
ArrayList lst = new ArrayList( rows);<br />
DataSet dsNew = new DataSet();<br />
dsNew.Tables.Add();<br />
<br />
for (int i=0; i<dsSource.Tables[0].Rows[0].ItemArray.Length + 1; i++)<br />
	dsNew.Tables[0].Columns.Add();<br />
<br />
foreach(DataRow drs in lst)<br />
{<br />
	ArrayList lst2 = new ArrayList(drs.ItemArray);<br />
	lst2.Insert(3, "INSERT VALUE");	//can be null						<br />
	DataRow ndr = dsNew.Tables[0].NewRow();<br />
	ndr.ItemArray = lst2.ToArray();												<br />
	dsNew.Tables[0].Rows.Add(ndr);<br />
}<br />

EDIT : hmm, the code tags seem to have messed up that for loop it should be :

for (int i=0; i

Multiple Events

Anonymous18-Jun-03 0:52

Anonymous

18-Jun-03 0:52

how do i get windows to notify me of multiple events? eg a mouse click and a mouse over another contorl at the same time?

i have a button and a panel, when i click and hold the mouse button down over the button an event is fired, if i keep the mouse button clicked and move over the panel the mouseover event for the panel is not fired, it is fired only when i relase the mouse button

is there a way of getting round this problem? i need to know the mouse over events occuring.

thanks

ListView Column Resize

somanath17-Jun-03 23:44

somanath

17-Jun-03 23:44

How can I trap an event when a column of listview control is resized in C#?

SmtpMail.Send exception

EnkelIk17-Jun-03 23:16

17-Jun-03 23:16

Hi.

I'm having problems with code that worked until just recently. I have a C# komponent which uses SmtpMail to send an e-mail, but now I get an exception. With stack trace it looks like follows:
[SEHException (0x80004005): External component has thrown an exception.]
System.RuntimeType.CreateInstanceImpl(Boolean publicOnly) +0
System.Activator.CreateInstance(Type type, Boolean nonPublic) +66
System.Web.Mail.CdoSysHelper.Send(MailMessage message) +64
System.Web.Mail.SmtpMail.Send(MailMessage message) +150

The component still works on my normal computer (where I run XP) and the only thing I can remember doing on the mashine acting as server (running Win2000) is that I uninstalled IE 6, because I wanted to see a webpage in IE 5.5. It didn't feel like it should matter but now the component does not work. I have reinstalled IE 6 and updated with all the latest patches and so on, but it still wont work. Can there be some setting that may have changed and now is preventing an instance from some component to be created?

Code sample:
MailMessage vscMail=new MailMessage();

vscMail.To="myemail@hotmail.com";
vscMail.From="myemail@hotmail.com";
vscMail.Subject="Sending an e-mail";
vscMail.Body="Hello world!";

SmtpMail.SmtpServer=strSmtpServer;
SmtpMail.Send(vscMail);

Any idéas or hints?

Thanks
/EnkelIk

EnkelIk18-Jun-03 0:53

18-Jun-03 0:53

Version 1.0.3705 on both. On the one where it works I have complete Visual Studio .Net installed, on the one it doesn't work I just have the framework.

EnkelIk18-Jun-03 1:43

18-Jun-03 1:43

I tried installing Framework 1.1, but unfortunatelly it didn't help.

EnkelIk18-Jun-03 21:39

18-Jun-03 21:39

So far .net 1.1 seems neither to have helped nor harmed -it still doesn't work.

I got the idea that the trouble could be in the connection to the smtp-server so I tried setting the SmtpMail.Server to "localhost" (and also not to set it at all) but the exception was the same, even when I stopped the Default SMTP virtual server running on the "win2000-machine". My conclusion is that the exception occurs before the application even tries to connect to the smtp-server.

Do you think uninstalling .net frameworks all together and then reinstalling it might help?

Thanks
/EnkelIk

EnkelIk22-Jun-03 20:38