Re: OleDbException error - C# Discussion Boards

21-Jul-05 9:02

I'm putting together my first C# database application. It compiles fine and seems to be connecting to my database fine, but when I create the command I get the following error:

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in system.data.dll

This is the line VS claims is causing the error:
this.cmdGetNewClients = new System.Data.OleDb.OleDbCommand();

The code around it is:

this.cn.Open();
this.cmdGetNewClients = new System.Data.OleDb.OleDbCommand();
cmdGetNewClients.CommandText = @"SELECT ClientName FROM Clients";
cmdGetNewClients.Connection = this.cn;
OleDbDataReader rdr = cmdGetNewClients.ExecuteReader();
while(rdr.Read())
newClients.Add(rdr["[Client Name]"]);
rdr.Close();
cn.Close();

Can anyone tellme why I'm getting this error and how to fix it?\

Thanks!

The ends can never justify the means. It is the means that determine the ends.

squawk21-Jul-05 9:12

21-Jul-05 9:12

The error is too general. Wrap the code in a try catch block and see what the true error is.
If you catch and exception of type SqlException you can try this:
foreach(SqlError err in sqlEx.Errors)
Console.Writeline(e.Message);
Otherwise just check the InnerException. It could be something simple like a login issue.

theStorminMormon21-Jul-05 9:23

21-Jul-05 9:23

Thanks for the advice, can you give me a hand writing the try/catch though? I'm afraid I'm a bit new to C# and rusty in the other stuff I knew in college.

it would go something like this:

try
{
this.cmdGetNewClients = new System.Data.OleDb.OleDbCommand();
}
catch()
{
foreach(SqlError err in sqlEx.Errors)
console.WriteLine(e.Message);
}

What goes in the catch()?

Thanks so much for helping.

The ends can never justify the means. It is the means that determine the ends.

squawk21-Jul-05 9:31

21-Jul-05 9:31

Try something like this:
try
{
//insert your code here
}
catch(OleDbException ex)
{
Console.WriteLine("Message: " + ex.Message + "\n");
if(ex.InnerException != null)
Console.WriteLine("Message: " + ex.InnerException.Message + "\n");
foreach(OleDbError e in ex.Errors)
Console.WriteLine(e.Message + "\n");
}

theStorminMormon21-Jul-05 9:41

21-Jul-05 9:41

OK, I got that coded in, but it doesn't seem to be actually catching the error. It's highlighting the lind of code inside the try, but it's still saying it's an "unhandled exception" and I'm not getting any console output.

What gives now?

The ends can never justify the means. It is the means that determine the ends.

Rob Graham21-Jul-05 9:42

Rob Graham

21-Jul-05 9:42

Possibly a typo in your post, but...
you select a field named [ClientName] (no space)
then try to get the field value from [Client Name] (space btwn Client & Name)
no such field exists in the readr, so an exception is thrown.

Absolute faith corrupts as absolutely as absolute power
Eric Hoffer
The opposite of the religious fanatic is not the fanatical atheist but the gentle cynic who cares not whether there is a god or not.
Eric Hoffer

theStorminMormon21-Jul-05 9:46

21-Jul-05 9:46

Thanks for spotting that. It was actually an error in the code (I'd renamed the field and forgotten to update all references to it), but it's not causing the error. The code doesn't even get that far.

The ends can never justify the means. It is the means that determine the ends.

squawk21-Jul-05 10:01

21-Jul-05 10:01

I took your code and for the most part is worked ok. I filled in some of the blanks and got this code to complie and run:

OleDbConnection cn = new OleDbConnection("User ID=xxx;Password=xxx;Initial Catalog=Northwind;Data Source=192.168.0.1;Provider=SQLOLEDB");
cn.Open();
System.Data.OleDb.OleDbCommand cmdGetNewClients = new System.Data.OleDb.OleDbCommand();
cmdGetNewClients.CommandText = @"SELECT LastName FROM Employees";
cmdGetNewClients.Connection = cn;
OleDbDataReader rdr = cmdGetNewClients.ExecuteReader();
ArrayList newClients = new ArrayList();
while(rdr.Read())
newClients.Add(rdr["LastName"]); <-- change made here
rdr.Close();
cn.Close();

Good luck.

Luis Alonso Ramos21-Jul-05 10:40

refresh form from another form

21-Jul-05 10:40

Maybe you are forgetting to set the connection string in the OleDbConnection object.

-- LuisR

Luis Alonso Ramos
Intelectix - Chihuahua, Mexico

Not much here: My CP Blog!

webhay21-Jul-05 8:35

webhay

21-Jul-05 8:35

Hello All,

I Lunch a form from another form how can i refresh the Firest form after I click button on the second form.

Regards
Hay

Re: refresh form from another form

Piovra_21-Jul-05 21:32

Piovra_

21-Jul-05 21:32

if you launch the second form from the first one you can add the first form in de constructor of the second. Something like

private Form m_form1<br />
<br />
public Form2(Form form1)<br />
{<br />
  m_form1 = form1<br />
}<br />
<br />
your button click would be someting like:<br />
<br />
<code>private void HandleClick()<br />
{<br />
  m_form1.Refresh();<br />
}<br />
<br />
basically you can call any public method in form1.<br />
<br />
Other more advanced option is to use the observer pattern. You can google for observer and c# to get more info on that subject.<br />
<br />
<br />

DataGrid question

zaboboa21-Jul-05 7:48

zaboboa

21-Jul-05 7:48

Hello,

I have a datagrid:

this.dataGridRevenues.DataMember = "LotYields";
this.dataGridRevenues.DataSource = this.dataset;

is there a way to display only certain rows in the grid, when loading the
dataset?

Thank you.

Re: DataGrid question

Alomgir Miah21-Jul-05 8:02

Alomgir Miah

21-Jul-05 8:02

Try this

this.dataset.Tables("Products").Columns("Name").ColumnMapping = MappingType.Hidden

Alomgir Miah
Live Life King Size

Re: DataGrid question

squawk21-Jul-05 9:05

Finding when items are added or removed in a ListView

21-Jul-05 9:05

Hello,

If you want to display specific rows based on the values they contain, you can create a DataView, and set the RowFilter property. Then bind the Datagrid to the DataView.

Re: DataGrid question

Tom Wright21-Jul-05 11:04

Tom Wright

21-Jul-05 11:04

you can also create your select statement to only return the rows you want. Which to me would seem to be the easiest.

Tom Wright
tawright915@yahoo.com

Luis Alonso Ramos21-Jul-05 7:28

DataGridComboBoxColumn does not exit

21-Jul-05 7:28

Hello,

I'm writing a little class that hooks up a list view to display the selection count in the status bar. It's working great except that I found one little problem: in one of my forms, I have a tree control on the left, and a list view on the right. If I select another item in the tree, the list view is cleared and filled again with some other items (unselected, of course), but I never get the SelectedIndexChanged event.

Is there anyway I could detect when a new item is added and just update the count display? The only restriction is that I can't modify existing code.

Any ideas?

-- LuisR

Luis Alonso Ramos
Intelectix - Chihuahua, Mexico

Not much here: My CP Blog!

zaboboa21-Jul-05 6:26

zaboboa

21-Jul-05 6:26

Hello,

I am trying to add a combobox to the datagrid, but I get an error
stating:

The type or namespace name 'DataGridComboBoxColumn' could not be found (are you missing a using directive or an assembly reference?)

I think I have all the directives, but maybe I am missing something?

Re: DataGridComboBoxColumn does not exit

Luis Alonso Ramos21-Jul-05 7:24

Re: DataGridComboBoxColumn does not exit

21-Jul-05 7:24

I you are using .NET 1.x, then no, it doesn't exist. There are, however, several good articles explaining how to implement one here in CodeProject. Just search.

-- LuisR

Luis Alonso Ramos
Intelectix - Chihuahua, Mexico

Not much here: My CP Blog!

zaboboa21-Jul-05 7:44

zaboboa

21-Jul-05 7:44

I can't find an article that would concentrate on .NET 1.x, all of them
assume that you use higher version.

Re: DataGridComboBoxColumn does not exit

Luis Alonso Ramos21-Jul-05 7:47