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hi all i have this pro on hand now.. i have downloaded some sample database applications from the internet..however when i want to debug it i gives me the error--An unhandled exception of type "system.Data.OleDb.OledbException" occurred in system.data.dll
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.OleDb;
namespace Database_Example
{
///
/// Summary description for Form1.
///
public class fclsMain : System.Windows.Forms.Form
{
OleDbConnection m_cnADONewConnection = new OleDbConnection();
OleDbDataAdapter m_daDataAdapter = new OleDbDataAdapter();
DataTable m_dtContacts = new DataTable();
int m_rowPosition = 0;
private System.Windows.Forms.TextBox txtContactName;
private System.Windows.Forms.TextBox txtState;
private System.Windows.Forms.Button btnMoveFirst;
private System.Windows.Forms.Button btnMovePrevious;
private System.Windows.Forms.Button btnMoveNext;
private System.Windows.Forms.Button btnMoveLast;
private System.Windows.Forms.Button btnSave;
private System.Windows.Forms.GroupBox grpNewRecord;
private System.Windows.Forms.TextBox txtNewContactName;
private System.Windows.Forms.TextBox txtNewState;
private System.Windows.Forms.Button btnAddNew;
private System.Windows.Forms.Button btnDelete;
///
/// Required designer variable.
///
private System.ComponentModel.Container components = null;
public fclsMain()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after InitializeComponent call
//
}
///
/// Clean up any resources being used.
///
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///
private void InitializeComponent()
{
this.txtContactName = new System.Windows.Forms.TextBox();
this.txtState = new System.Windows.Forms.TextBox();
this.btnMoveFirst = new System.Windows.Forms.Button();
this.btnMovePrevious = new System.Windows.Forms.Button();
this.btnMoveNext = new System.Windows.Forms.Button();
this.btnMoveLast = new System.Windows.Forms.Button();
this.btnSave = new System.Windows.Forms.Button();
this.grpNewRecord = new System.Windows.Forms.GroupBox();
this.txtNewContactName = new System.Windows.Forms.TextBox();
this.txtNewState = new System.Windows.Forms.TextBox();
this.btnAddNew = new System.Windows.Forms.Button();
this.btnDelete = new System.Windows.Forms.Button();
this.grpNewRecord.SuspendLayout();
this.SuspendLayout();
//
// txtContactName
//
this.txtContactName.Location = new System.Drawing.Point(48, 112);
this.txtContactName.Name = "txtContactName";
this.txtContactName.Size = new System.Drawing.Size(112, 20);
this.txtContactName.TabIndex = 0;
this.txtContactName.Text = "";
//
// txtState
//
this.txtState.Location = new System.Drawing.Point(168, 112);
this.txtState.Name = "txtState";
this.txtState.Size = new System.Drawing.Size(80, 20);
this.txtState.TabIndex = 1;
this.txtState.Text = "";
//
// btnMoveFirst
//
this.btnMoveFirst.Location = new System.Drawing.Point(16, 152);
this.btnMoveFirst.Name = "btnMoveFirst";
this.btnMoveFirst.Size = new System.Drawing.Size(32, 23);
this.btnMoveFirst.TabIndex = 2;
this.btnMoveFirst.Text = "<<";
this.btnMoveFirst.Click += new System.EventHandler(this.btnMoveFirst_Click);
//
// btnMovePrevious
//
this.btnMovePrevious.Location = new System.Drawing.Point(56, 152);
this.btnMovePrevious.Name = "btnMovePrevious";
this.btnMovePrevious.Size = new System.Drawing.Size(32, 23);
this.btnMovePrevious.TabIndex = 3;
this.btnMovePrevious.Text = "<";
this.btnMovePrevious.Click += new System.EventHandler(this.btnMovePrevious_Click);
//
// btnMoveNext
//
this.btnMoveNext.Location = new System.Drawing.Point(96, 152);
this.btnMoveNext.Name = "btnMoveNext";
this.btnMoveNext.Size = new System.Drawing.Size(32, 23);
this.btnMoveNext.TabIndex = 4;
this.btnMoveNext.Text = ">";
this.btnMoveNext.Click += new System.EventHandler(this.btnMoveNext_Click);
//
// btnMoveLast
//
this.btnMoveLast.Location = new System.Drawing.Point(136, 152);
this.btnMoveLast.Name = "btnMoveLast";
this.btnMoveLast.Size = new System.Drawing.Size(32, 23);
this.btnMoveLast.TabIndex = 5;
this.btnMoveLast.Text = ">>";
this.btnMoveLast.Click += new System.EventHandler(this.btnMoveLast_Click);
//
// btnSave
//
this.btnSave.Location = new System.Drawing.Point(176, 152);
this.btnSave.Name = "btnSave";
this.btnSave.Size = new System.Drawing.Size(40, 23);
this.btnSave.TabIndex = 6;
this.btnSave.Text = "Save";
this.btnSave.Click += new System.EventHandler(this.btnSave_Click);
//
// grpNewRecord
//
this.grpNewRecord.Controls.AddRange(new System.Windows.Forms.Control[] {
this.btnAddNew,
this.txtNewState,
this.txtNewContactName});
this.grpNewRecord.Location = new System.Drawing.Point(16, 192);
this.grpNewRecord.Name = "grpNewRecord";
this.grpNewRecord.Size = new System.Drawing.Size(264, 64);
this.grpNewRecord.TabIndex = 7;
this.grpNewRecord.TabStop = false;
this.grpNewRecord.Text = "New Contact";
//
// txtNewContactName
//
this.txtNewContactName.Location = new System.Drawing.Point(8, 24);
this.txtNewContactName.Name = "txtNewContactName";
this.txtNewContactName.Size = new System.Drawing.Size(112, 20);
this.txtNewContactName.TabIndex = 0;
this.txtNewContactName.Text = "";
//
// txtNewState
//
this.txtNewState.Location = new System.Drawing.Point(126, 24);
this.txtNewState.Name = "txtNewState";
this.txtNewState.Size = new System.Drawing.Size(80, 20);
this.txtNewState.TabIndex = 1;
this.txtNewState.Text = "";
//
// btnAddNew
//
this.btnAddNew.Location = new System.Drawing.Point(214, 24);
this.btnAddNew.Name = "btnAddNew";
this.btnAddNew.Size = new System.Drawing.Size(40, 23);
this.btnAddNew.TabIndex = 2;
this.btnAddNew.Text = "Add";
this.btnAddNew.Click += new System.EventHandler(this.btnAddNew_Click);
//
// btnDelete
//
this.btnDelete.Location = new System.Drawing.Point(224, 152);
this.btnDelete.Name = "btnDelete";
this.btnDelete.Size = new System.Drawing.Size(56, 23);
this.btnDelete.TabIndex = 8;
this.btnDelete.Text = "Delete";
this.btnDelete.Click += new System.EventHandler(this.btnDelete_Click);
//
// fclsMain
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.btnDelete,
this.grpNewRecord,
this.btnSave,
this.btnMoveLast,
this.btnMoveNext,
this.btnMovePrevious,
this.btnMoveFirst,
this.txtState,
this.txtContactName});
this.Name = "fclsMain";
this.Text = "Database Example";
this.Load += new System.EventHandler(this.fclsMain_Load);
this.Closed += new System.EventHandler(this.fclsMain_Closed);
this.grpNewRecord.ResumeLayout(false);
this.ResumeLayout(false);
}
#endregion
///
/// The main entry point for the application.
///
[STAThread]
static void Main()
{
Application.Run(new fclsMain());
}
private void fclsMain_Load(object sender, System.EventArgs e)
{
m_cnADONewConnection.ConnectionString =
@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\temp\contacts.mdb";
m_daDataAdapter =
new OleDbDataAdapter("Select * From Contacts",m_cnADONewConnection);
OleDbCommandBuilder m_cbCommandBuilder = new OleDbCommandBuilder(m_daDataAdapter);
m_daDataAdapter.Fill(m_dtContacts);
this.ShowCurrentRecord();
}
private void fclsMain_Closed(object sender, System.EventArgs e)
{
m_cnADONewConnection.Close();
}
private void ShowCurrentRecord()
{
if (m_dtContacts.Rows.Count==0)
{
txtContactName.Text = "";
txtState.Text = "";
return;
}
txtContactName.Text =
m_dtContacts.Rows[m_rowPosition]["ContactName"].ToString();
txtState.Text = m_dtContacts.Rows[m_rowPosition]["State"].ToString();
}
private void btnMoveFirst_Click(object sender, System.EventArgs e)
{
m_rowPosition = 0;
this.ShowCurrentRecord();
}
private void btnMovePrevious_Click(object sender, System.EventArgs e)
{
if (!(m_rowPosition == 0))
{
m_rowPosition = m_rowPosition-1;
this.ShowCurrentRecord();
}
}
private void btnMoveNext_Click(object sender, System.EventArgs e)
{
if (!(m_rowPosition == m_dtContacts.Rows.Count-1))
{
m_rowPosition = m_rowPosition + 1;
this.ShowCurrentRecord();
}
}
private void btnMoveLast_Click(object sender, System.EventArgs e)
{
if(!(m_dtContacts.Rows.Count==0))
{
m_rowPosition = m_dtContacts.Rows.Count-1;
this.ShowCurrentRecord();
}
}
private void btnSave_Click(object sender, System.EventArgs e)
{
if (!(m_dtContacts.Rows.Count==0))
{
m_dtContacts.Rows[m_rowPosition]["ContactName"]= txtContactName.Text;
m_dtContacts.Rows[m_rowPosition]["State"] = txtState.Text;
m_daDataAdapter.Update(m_dtContacts);
}
}
private void btnAddNew_Click(object sender, System.EventArgs e)
{
DataRow drNewRow = m_dtContacts.NewRow();
drNewRow["ContactName"] = txtNewContactName.Text;
drNewRow["State"] = txtNewState.Text;
m_dtContacts.Rows.Add(drNewRow);
m_daDataAdapter.Update(m_dtContacts);
m_rowPosition = m_dtContacts.Rows.Count-1;
this.ShowCurrentRecord();
}
private void btnDelete_Click(object sender, System.EventArgs e)
{
if (!(m_dtContacts.Rows.Count==0))
{
m_dtContacts.Rows[m_rowPosition].Delete();
m_daDataAdapter.Update(m_dtContacts);
m_rowPosition=0;
this.ShowCurrentRecord();
}
}
}
}
does this errors occur due to where the dB file is located..is it correct? can someone out there help will this pro? and maybe guide me to correcting it ..thanks in advance..
the whole chunk of codes is written below,the pro is highlighted in bold...thanks in advance
one of the ans i got is entering cnADONewConnection.Open();
before m_daDataAdapter.Fill(m_dtContacts);
but i got an error like this C:\Documents and Settings\STUDENT\Desktop\Database Example\Form1.cs(235): The type or namespace name 'cnADONewConnection' could not be found (are you missing a using directive or an assembly reference?)
can anyone please give me more detailed help as im really new to this
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I'd honestly recommend learning core Winforms programming until you understand which bits of the code you pasted above are absolutely useless in trying to diagnose your problem. Then worry about databases.
And in future, whatever bugs you have, try stepping through the code so you know where the actual problem is. That's how programmers solve bugs, we look at the code line by line, until we see where the program isn't doing what we expect or hoped.
You've probably just got a wrong connection string.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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skyeddie wrote: one of the ans i got is entering cnADONewConnection.Open();
before m_daDataAdapter.Fill(m_dtContacts);
but i got an error like this C:\Documents and Settings\STUDENT\Desktop\Database Example\Form1.cs(235): The type or namespace name 'cnADONewConnection' could not be found (are you missing a using directive or an assembly reference?)
Maybe because in yor code the name is actually m_cnADONewConnection. Someting one would expect you to recognise...
The constructor overload you are using for the OleDbDataAdaptor creates one that opens and closes the connection with each fill operation, so you shouldn't need the Open().
Is the database really where the connection string says it is?
Is it writeable?
Is it really an access database?
Put a breakpoint in the beginning of the Load event handler, say the first line, then single step to see which line is causing the exeption.
Add some error handling (try-catch in the load handler would be nice, so the app wouln't need to just evaporate on the current error)
And next time, just post the code causing the problem, not the whole bloody form. Most of us won't waste our time hunting through 500 lines of code to see what you're talking about.
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wht the .. some people say "plz post more details then some say post a section" wht u all programmers r thinking actually.. anyway wht useless ans u all give.. i have found out the ans myself !! all u supposingly smart ass jus didnt provide any help .. im new in c# yet i solve myself..haha!!
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Congratulations. you just made my list of posters to ignore in the future. Glad you're able to solve your own problems, because you are certainly going to get to in the future...
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hey
i am developing a web application using asp.net, but coding in C#.
i need to insert into my database (sql server 2000/access). how shud i do it.
i have two textboxes.. watever the user enters in it, it shud be added in a particular table.
Kunal Piyush
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shud ?
The fact that your ASP.NET codebehind runs on the server means the code is no different to accessing a database using WinForms. Any help you can find on the web for database access will work just fine.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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i coded a bit.. but now sql database i showing an error if i keep the field "Username" as a primary key.
firstly the data is entered in a very ad-hoc fashion.. there is a row empty at the top...data entered in between two rows which are already filled with data..
and if i delete some data,then i get the error as
"Another user has modified the contents of the table,the database row ur modifying no longer exists in the database....... violation of PRIMARY KEY constraint...."
THE CODE:-
try
{
SqlConnection conn = new SqlConnection("server=(local);" +
"database=path;" +
"connection timeout=3;" +
"Trusted_Connection=yes;" +
"Integrated Security=true;" +
"user id=sa;" +
"password=");
conn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "Insert into login(Username,Password) values('"+uname.Text+"','"+pass.Text+"')" ;
SqlDataReader dread = cmd.ExecuteReader();
if (dread.Read())
{
failed.Text = "Could not add the user";
}
else
{
Response.Redirect("success.aspx");
}
conn.Close();
}
catch(Exception kp)
{
failed.Text=kp.Message;
}
}
Kunal Piyush
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the question is simply this boys n girls, ladies n gents,
how do I iterate thru all the elements of a Datagrid in a windows form (.net 1.1). thats when I take input from user. how do i know the number of rows entered in it.
thanks
I'd appreciate if u tel me that in c# but anyways tahts not compulsory
thanks in advance
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Doesn't the DataGrid have a Rows property, which has a Count property ?
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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OK got ur point, stupid question I know
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wait a second here I think this property is not therein Windows Forms, I might still be wrong though, I'm sorry for taht in advance but I got the other way around to this like
DataTable dt = (DataTable) dg.DataSource;
dt.Rows.Count
casting the DataGrids Datasource into a table and then using its count
but I'm not so sure if it will work when the using is giving data for input
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Just one more question here, God I'm a real new commer here,
ah how do u empty a datagrid.
I want the datagrid showing an existing set of records to get empty when I click a button for adding a new record. Its actually a master detail form. The master table is linked with a set of textboxes and comboboxes and The details are in the datagrid. I hope the scenario is clear now and I repeat I'm using .net 1.1 and working in Windows Forms. So I need the info abt System.windows.Forms not the other one
thanks in advance...
Rocky
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clear the datascource
grdDetails.DataSource = Nothing
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Thanks I got this idea a little while b4 I read this but I really appreciate it.
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Well right now I'm working on that same form to save the data. I've made the sqlDataadapters for the master and the detail tables which offcourse have the update,select insert, del commands.
But I'm a bit confused in whether if I should add() the new row of data in the master table b4 taking the input from the datagrid or not.
Can anyone plz give me a few guidlines or a tip or 2 abt this. I'm doin this for the first time actually. If u can give any useful Urls, that wuold be nice too.
thanks
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Can anybuddy provide me some good helping material (reading, code etc) for making master detail forms (C# preferably)
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You can get so many examples on net for that if you will use google : 
here is the one:
http://msdn2.microsoft.com/en-us/library/c12c1kx4.aspx
Best Regards,
Apurva Kaushal
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Thanks a lot, I appreciate it. yesterday I worked on the form and its del command is working allright now. I havent worked on updates as yet.
I'm having a little problem in inserting data in the detail table. Its shown in a datagrid and I dont know, the records get inserted automatically thru the grid. Its strange for me. How can we stop this behaviour ir use it more inteligently for our purpose?
Thanks a lot...
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private void MakeReadOnly()
{
dataGridView1.AllowUserToAddRows = false;
dataGridView1.AllowUserToDeleteRows = false;
dataGridView1.ReadOnly = true;
}
I think I got the clue here. is that it?
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I had a hard time installing MSDE 2000 onto my system but I eventually did. However, when I check my add remove programs all I see in there is Microsoft SQL CE 2.0 Server Tool but no SQL server. Futhermore everytime I re-start I get a message that states:"The system can not find the file specified". First I am not sure if MSDE was fully installed, since I was getting an error message before. Second: I am not sure how to assign service to application since its computer name appears in there but yet it can nto find service.
1. So my question is how do I assign service to SQL server?
2. How do I know that it is MSDE that is installed?
3. I am getting an error when attempting to start MSSQL Server AD Helper?
Thanks and any information which can help will be greatly appreciated.
Greg
Coding makes the world go round!!!
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1. You shouldn't have to do anything, install should take care of this.
2. from your description, it's not. You should be able to open the services admin tool , and see mssqlserver service. you should be able to start and stop it. There shouldbe a small "server" icon in the system tray (XP). A right click there should get "open Sql Server Manager" as a menu item. from the manager you should be able to start/stop the server, Sql Server agent and DTC.
3. if the server itself is not running, the AD helper can't start.
I would uninstall and try again (what problems did you have installing it - what OS are you installing to?)
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I restarted and before I knew it was up and running fine with service and everything. Thanks
PS: I was using XP.
Greg
Coding makes the world go round!!!
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select SUBSTRING(dmv2_data_text, 40, DATALENGTH(DMV2_DATA_TEXT))
from dmv2 WHERE DMV2_RCD_TYPE = 'R'
When I run this query sometimes there's a carriage return sometimes there isn't. Is there a way to inspect the first char and see if there is a CR and if so shift the whole string over one more space to remove it?
Thanks
Tom Wright
tawright915@gmail.com
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SELECT CASE WHEN SUBSTRING(dmv2_data_text, 40, 1) = CHAR(13)
THEN SUBSTRING(dmv2_data_text, 42, DATALENGTH(DMV2_DATA_TEXT))
ELSE SUBSTRING(dmv2_data_text, 40, DATALENGTH(DMV2_DATA_TEXT))
END
FROM dmv2 WHERE DMV2_RCD_TYPE = 'R'
If it is a carraige return, then add two (carriage return + line feed).
--EricDV Sig---------
Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them.
- Laurence J. Peters
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