Develop Reference

i am getting an error at oledbdatareader saying no given value for one or more required parameters in ASP.NET

I have a webpage called blogwebsite and in that I have a textbox and search button. I am passing the value of textbox on button click to another webform called blogseacrh through session. I also have a database bound through these webforms. In this blogsearch webpage I have taken the session variable in a textbox. Using this textbox value I am writing a oledbcommand select query. I am fetching data from the database using this textbox value and want to display it on the blogsearch webpage. For this to happen I am using oledbdatareader to read the data and then write the fetched data in the textbox. But when I am running the webpage when I click on search button it gives me the error at the oledbdatareader line saying that no given value given for one or more required parameters.
I really can't understand what I am doing wrong. Can someone please give me a solution?
This is the button click event which is working perfectly
protected void btn_srch_Click(object sender, EventArgs e)
{
Session["name"] = txt_bnm.Text;
Response.Redirect("blogseacrh.aspx");
}
This is the code that needs to be executed on another webpage on button click event
protected void Page_Load(object sender, EventArgs e)
{
if (Session["name"] != null)
{
con.Open();
txt2_bnm.Text = Session["name"].ToString();
cmd = new OleDbCommand("select user from tbl_blogs where book_name='" + txt2_bnm.text + "',con); `
OleDbDataReader d = cmd.ExecuteReader();
while (d.Read())
{
user = d["user"].ToString();
Response.Write(user);
}
cmd = new OleDbCommand("select blogs from tbl_blogs where book_name='" + txt2_bnm.Text + "' ", con);
OleDbDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
blogs = dr["blogs"].ToString();
Response.Redirect(blogs);
}
con.Close();
}
I have also checked all the field names and table name and they are all correct as well.
Can someone please solve this error. i have an assignment to complete please.

ASPxGridView DeleteRow not deleting on another control callback

I'm using the DEVExpress's gridview and have this code that deletes the selected gridview row from another control's customcallback,
the line
GridFrom.DeleteRow(int.Parse(rowKey[2]));
retrieves the correct visibleIndex but does not remove the row from the gridview. The databind also does not refreshes the gridview's data and it requires refreshing of the page for the data to update
protected void ASPxTreeList1_CustomCallback(object sender, DevExpress.Web.ASPxTreeList.TreeListCustomCallbackEventArgs e)
{
string[] rowKey = e.Argument.Split('|');
string strConnectionString = ConfigurationManager.ConnectionStrings["dbname"].ConnectionString;
using (SqlConnection conn = new SqlConnection(strConnectionString))
{
string query = "DELETE FROM Table WHERE id=#id";
using (SqlCommand cmd = new SqlCommand(query, conn))
{
conn.Open();
cmd.Parameters.AddWithValue("#id", rowKey[0]);
cmd.ExecuteNonQuery();
conn.Close();
}
}
GridFrom.DeleteRow(int.Parse(rowKey[2])); //rowKey[2] is the visibleIndex
GridFrom.DataBind();
}
}

it requires refreshing of the page for the data to update
You don't see grid changes, because ONLY ASPxTreeList is updated during ITS OWN callback.
As a possible solution, disable ASPxTreeList's callbacks or delete a grid row using the grid's CustomCallback instead (in a similar manner).
<dx:ASPxTreeList ID="ASPxTreeList1" runat="server" EnableCallbacks="false">
</dx:ASPxTreeList>
Check the The concept of callbacks - Why is it impossible to update external control data during a callback to another control learning guide regarding this.

Refresh GridView After Data is Deleted From DetailView Using C#

When user select any record from the GridView then my DetailView is updated based on the selection of the GridView. So what I am trying to do is that when I delete anything from the DetailView then I want to refresh the GridView so basically I don’t want to show still the deleted record in the GridView. I have tried to resolve this issue by doing the data bind after my connection and SQL statement but it does not refresh it. One thing to note is that I am using a Accordion pane but both my gridview and the detailview are on the same pane. I am not sure if this is breaking anything. Here is my code:
protected void Refresh_ItemCommand(object sender, DetailsViewCommandEventArgs e)
{
if (e.CommandName.Equals("Delete", StringComparison.CurrentCultureIgnoreCase))
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
SqlDataAdapter da = new SqlDataAdapter("select ID, Name, Address from dbo.MyTable", con);
DataTable dt = new DataTable();
da.Fill(dt);
Gridview1.DataSource = dt;
Gridview1.DataBind();
}
}

You may use the event of the Data view called "ItemDeleted" as follows:
DetailViewName_ItemDeleted(object sender,
DetailsViewDeletedEventArgs e)
{
// Refresh the GridView control after a new record is updated
// in the DetailsView control.
GridViewName.DataBind();
}
The above code is from the official MSDN site for detail view control.
The other way (which I prefer) is to handle the data grid during the Page_load procedure so when you press your delete button in the detail view, the page will perform a postback.
So in the procedure Page_load you can call another procedure which fills the data grid. The code might be like this:
if (isPostback)
{
FillGrid();
}
private void FillGrid()
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
SqlDataAdapter da = new SqlDataAdapter("select ID, Name, Address from dbo.MyTable", con);
DataTable dt = new DataTable();
da.Fill(dt);
Gridview1.DataSource = dt;
Gridview1.DataBind();
}

Your code doesn't show anything where the record is actually deleted so it's understandable that when you re-fetch the data still contains everything.
What you need to do is:
Execute a sql statement to delete the record
Re-fetch the data
Rebind the data.
If you follow those 3 steps it will work.

try to use the event that is called in case of pressing the delete key from the DGV
private void DGV_DeleteKeyPressed(object sender, KeyEventArgs e)
{
//enter code here
}

ASP.NET why Gridview Paging on page 2 and the rest of it are disappear?

I have so many list of ServerName in GridView, so I decide to add paging. The data show list result on page 1 but on page 2 and the rest of it is not display anything. I already have OnPageIndexChanging="GridViewServer_PageIndexChanging" in GridViewServer property. Please help! Here is c# code behind,
protected void GridViewServer_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
GridViewServer.PageIndex = e.NewPageIndex;
GridViewServer.DataBind();
}
A GridView binding function codes,
public void BindGridView()
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Database_Shared_NotebookConnectionString"].ConnectionString);
conn.Open();
string sqlquery = ("SELECT * FROM tblServer");
SqlCommand command = new SqlCommand(sqlquery, conn);
SqlDataAdapter adp = new SqlDataAdapter(command);
DataSet ds = new DataSet();
adp.Fill(ds);
GridViewServer.DataSource = ds.Tables[0];
GridViewServer.DataBind();
}

You need to set your GridView's datasource appropriately. You can't just call DataBind if the datasource isn't properly set. Basically what it amounts to is binding your GridView to null (which would have no page 2). I would recommend having a private method that is responsible for this process and whenever you need to bind you call that.
private void BindGridViewServer()
{
GridViewServer.DataSource = GetYourData(); // This should get the data
GridViewServer.DataBind();
}
Call this method from within your event with:
protected void GridViewServer_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
GridViewServer.PageIndex = e.NewPageIndex;
BindGridViewServer();
}
This could be made more extensible by passing in the GridView as a parameter, but you'd have to have other parameters as well to make sure the method retrieves the proper data.

Here's a very good tutorial (with sample code) on custom GridView paging. This makes the paging controls look like the familiar ones you see on a lot of search engines, forums, etc.
http://geekswithblogs.net/aghausman/archive/2009/05/18/custom-paging-in-grid-view.aspx

You have to give datasource to GridViewServer every time on page index changed.
so the code would be like this
protected void GridViewServer_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
GridViewServer.PageIndex = e.NewPageIndex;
GridViewServer.Datasource = MethodReturningDataTable();
GridViewServer.DataBind();
}

corrupt database & listbox problems

im working in WinForms C#.
for some reason when I want to populate my listBox it stops and says my database is corrupt.
I have added a repair line and the codes run afterwards, but nothing happends. My listbox is not populated.
Here is the code im using.:
public void button1_Click(object sender, EventArgs e)
{
SqlCeConnection cn = new SqlCeConnection(#"Data Source = Database1.mdf");
cn.Open();
SqlCeCommand cm = new SqlCeCommand("SELECT * FROM tblprojects ORDER BY Projekt_liste ASC", cn);
try
{
SqlCeDataReader dr = cm.ExecuteReader();
while (dr.Read())
{
ListBox project_list = Application.OpenForms["Form1"].Controls["tabControl1"].Controls["tabPage1"].Controls["Project_list"] as ListBox;
project_list.Items.Add(dr["Projekt_liste"].ToString());
}
cn.Close();
cn.Dispose();
}
catch (Exception ex)
{
}
}
public void button2_Click(object sender, EventArgs e)
{
SqlCeConnection cn = new SqlCeConnection();
SqlCeEngine engine = new SqlCeEngine("Data Source = Database1.mdf");
if (false == engine.Verify())
{
MessageBox.Show("Database is corrupted.");
engine.Repair(null, RepairOption.RecoverAllPossibleRows);
}
}

For example if you want to load the items
1. make sure you have a ListBox on the winform
2. name the ListBox
3. Create a ListItem
4 Add the ListItem to the ListBox
while(dr.Read())
{
ListViewItem obj=new ListViewItem(Convert.ToString(dr[0]),Convert.ToString(dr[1]);
//in object of ListViewItem give display member at first and give value member at second position
listView1.Items.Add(obj); // add object to the listbox
}
Here are a few links that you can use as well to show different ways on how to populate a ListBox
one is Windows and the other will be if you are using or plan to use ASP.NET
Populate a ListBox when using SQLDataReader
asp.net SqlDataReader example: how to use Read() method to populate ListBox
Populate ASP.NET ListBox using SqlDataReader

From Microsoft Site
The Repair method does not guarantee complete data recovery for every
database. Some forms of data corruptions cannot be repaired
completely, regardless of the Repair option that is selected by the
application.
This could be one of the case where your file is corrupted.
Also please try To have repair call straight above the call to populate Data in List.
This may help.