C# Discussion Boards - CodeProject

Jens Olsson7-Mar-06 5:22

Jens Olsson

7-Mar-06 5:22

Well, now I'm on track.

Invalidating the entire form was something I immediately felt was bad but I thought in a naive manner that it would work ok since I did't have that many controls.

Now I have to figure out how to adapt my program to this behaviour. There's plenty of data in an array that I obtain using an IPC call and after that I have to map all values to their respective controls. Right now the class that provides this array implements a delegate that the gui implements. From there I can easily access the array (ie the values read).

Well, that's off topic. If I change a property will it be invalidated no matter what? For instance, if I change the text property of a label, is any work done even if this control is on a tab page that is not visible? I mean, if I change values 4-5 times per sec I wouldn't want controls to be updated if they'r not visible...

[Marc]7-Mar-06 5:40

[Marc]

7-Mar-06 5:40

Uh, i don't know really. But what costs the most CPU is painting on the screen, running painting code that won't show on the screen doesn't really cost that much. Invalidate just tells Windows to update the control if it it shown on the screen i think. Otherwise Windows would really really suck Poke tongue | ;-P

.

But you can test it: attach an event handler to some paint event of a control that is on a tabpage that is not selected, so it is not visible. In the event handler you can write to the debug or something. Then change some property and see if the painting handler is raised.

What i do know: Refresh makes your control repaint instantly, while Invalidate tels Windows to 'repaint it if you have some time' or something like that. Multiple refreshes means multiple repaints, but multiple invalidates not per se. So always use Invalidate!

- Marc

"..Commit yourself to quality from day one..it's better to do nothing at all than to do something badly.."
-- Mark McCormick

|| Fold With Us! || Pensieve || VG.Net ||

Jens Olsson7-Mar-06 10:43

Jens Olsson

7-Mar-06 10:43

Yep, that's what I'm thinking too, the logic behind Invalidate should save work if it can and it probably does. I often tend to worry too much about things I shouldn't worry about at all... Wink | ;)

Well, I have wondered about the difference between Refresh and Invalidate and thought it would be something like that. Now I know, and that is quite useful to know.

Guess I have no excuses left, so it's just a matter of putting the pieces together now! Smile | :)

Thanks for all kind helpers!

regards

Jens

[Marc]7-Mar-06 10:50

[Marc]

7-Mar-06 10:50

No prob, happy coding! Big Grin | :-D

"..Commit yourself to quality from day one..it's better to do nothing at all than to do something badly.."
-- Mark McCormick

|| Fold With Us! || Pensieve || VG.Net ||

how to bind the data in datagrid using storedprocedure

Jens Olsson7-Mar-06 10:46

Jens Olsson

7-Mar-06 10:46

Yep, that's what I'm thinking too, the logic behind Invalidate should save work if it can and it probably does. I often tend to worry too much about things I shouldn't worry about at all... Wink | ;)

Thanks for all kind helpers!

regards

Jens

eswarattaluri5-Mar-06 21:56

eswarattaluri

5-Mar-06 21:56

hai,

how to bind the data in datagrid using storedprocedure.

thanks.

Re: how to bind the data in datagrid using storedprocedure

rccnh6-Mar-06 8:26

rccnh

6-Mar-06 8:26

Assuming the stored procedure is returning a result set to a DataSet, then just bind to the table returned within the DataSet. Use of a stored procedure versus a SQL Statement to retunr data has no effect on data binding.

Ron

How to show Values in CrystalReportViewer ???

Abubakarsb5-Mar-06 21:39

Abubakarsb

5-Mar-06 21:39

Hello,

I want to show Datagrid values in CrystalReportViewer by using C# can anybody send me sample code to do that? Please....

Regards,

AbuBakar

Re: How to show Values in CrystalReportViewer ???

albCode5-Mar-06 21:46

albCode

5-Mar-06 21:46

are u using WindowsApplication or WebApplication?

Re: How to show Values in CrystalReportViewer ???

Abubakarsb6-Mar-06 0:18

Abubakarsb

6-Mar-06 0:18

I am using Window Application not Web Application....

SQLDataReader Problem

Brendan Vogt5-Mar-06 21:22

Brendan Vogt

5-Mar-06 21:22

Hi all!!

I have a problem with the SQLDataReader. I don't understand it 100%. Please take a look at my code below for returning the titles to a combobox, it works fine just as it is:

public static IDataReader GetTitles()
{
SqlDataReader objDr = null;

// Create instance of connection and command object
SqlConnection objConn = new
SqlConnection(PLATTERGlobals.ConnectionString);
SqlCommand objCmd = new SqlCommand("sp_Title_GetAllTitles", objConn);

// Mark the command as a SPROC
objCmd.CommandType = CommandType.StoredProcedure;

// Add parameters to SPROC
SqlParameter[] objParamArray = new SqlParameter[] {};

// Execute the statement
try
{
objConn.Open();
objDr = objCmd.ExecuteReader();
}
catch (SqlException ex)
{
HandleError(objParamArray, ex, "sp_Title_GetAllTitles");
}
finally
{
if (objConn.State == ConnectionState.Open)
{
//objConn.Close();
}
//objConn.Dispose();
//objCmd.Dispose();
}

// Return the titles
return (objDr);

}

But I can't understand why I had to remove (//) my code in the finally block? I always like to close my connections and to dispose of them as soon as possible. But when I do it here, then it brings back a FieldCount error. Why is this? And when is the connection closed and destroyed? Do I still have to close explicitly?

Please can someone advise.

Regards

Guffa5-Mar-06 21:58

Guffa

5-Mar-06 21:58

The connection has to be open as long as you use the data reader.

You can specify CommandBehavior.CloseConnection when you create the reader to make the reader close the connection when the reader is closed, otherwise you have to close it explicitly.

Personaly I prefer to explicitly close the connection.

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b { font-weight: normal; }

Brendan Vogt5-Mar-06 22:17

Brendan Vogt

5-Mar-06 22:17

Hey!!

All that I want to do is populate a combo box with titles, like Mr, Mrs, Miss, etc. Is this the best way to go about it? I don't like to have an open connection all the time.

Guffa5-Mar-06 22:27

Guffa

5-Mar-06 22:27

You only have to keep the connection open as long as you read from the data reader.

Open the connection, get the reader, read from it and put the data in the control, close the reader and close the connection.

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b { font-weight: normal; }

Brendan Vogt5-Mar-06 22:48

Brendan Vogt

5-Mar-06 22:48

I understand what you are trying to say, but my confusion comes in because I am returning the SQLDataReader to the combo box.

In my register.aspx.cs file I call the Member class's static GetTitles method like this:

cboTitles.DataSource = Member.GetTitles();
cboTitles.DataValueField = "TitleID_PK";
cboTitles.DataTextField = "TitleName";
cboTitles.DataBind();

The static GetTitles method looks like this in the Member class:

public static IDataReader GetTitles()
{
return MemberDA.GetTitles();
}

And the return method I have posted already. So I'm still confused as to where I must close the SQLDataReader.

Regards

Guffa5-Mar-06 23:48

Guffa

5-Mar-06 23:48

You have to close the data reader after you have read all the data you need from it. In your code you would have to do that after the call to DataBind.

When you are moving data through several layers, you should consider to read the data into a DataSet, or a list of objects.

If you create a title class that has the properties you need in the combo box, you can use an ArrayList of such objects as a data source:

Class Title {

	private int id;
	private string name;

	public Title(int id, string name) {
		this.id = id;
		this.name = name;
	}

	public int TitleID_PK { get { return this.id; } }
	public string TitleName { get { return this.name; } }

}

You create the ArrayList by reading through the data reader:

ArrayList list = new ArrayList();
while (reader.Read()) {
	list.Add(new Title(reader.GetInt32("TitleID_PK"), reader.GetString("TitleName")));
}
reader.Close();

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b { font-weight: normal; }

create new column

angelagke5-Mar-06 21:18

angelagke

5-Mar-06 21:18

How to create new column to display at datagrid??

DataSet ds = new DataSet();

DataTable t = new DataTable();

ds.Tables.Add(t);

DataColumn cNo = new DataColumn("No", Type.GetType ("System.Int32"),"");
cNo.AutoIncrement = true;
cNo.AutoIncrementSeed = 1;
cNo.AutoIncrementStep = 1;
t.Columns.Add(cNo);

those is wat i hav write, but stil can display the new column?? Confused | :confused:

angela

albCode5-Mar-06 21:22

albCode

5-Mar-06 21:22

after u add new column try to refresh ur table or close ur SqlConnection and open again

angelagke5-Mar-06 22:40

angelagke

5-Mar-06 22:40

just wonder isn't my coding is put before

myConnection.Open();
da.Fill(ds);
myConnection.Close();

or after tat statement??

wat d coding for refresh function?? Cry | :((

angela

rah_sin6-Mar-06 1:05

rah_sin

6-Mar-06 1:05

i think u r adding datatable in dataset before adding column to datatable.
so try to add data table after adding datacolumn to datatable.

rahul

albCode6-Mar-06 2:54

albCode

6-Mar-06 2:54

DataSet ds = new DataSet();

DataTable t = new DataTable();

ds.Tables.Add(t);

DataColumn cNo = new DataColumn("No", Type.GetType ("System.Int32"),"");
cNo.AutoIncrement = true;
cNo.AutoIncrementSeed = 1;
cNo.AutoIncrementStep = 1;
t.Columns.Add(cNo);

//1. close ur sqlconnection
//2. load ur data from ur table (select commad example: select * from urtable(when u give select * command then u can view ur new column...))
//3. open ur connection string