Need Help with Database Update using DataAdaptor - C# Discussion Boards

Don't use the row index to obtain a row from a related table, use a foreign key relationship.

led mike

Thanks Mike....that makes total sense now. Am I going about this the best way, or is there a better method I should follow? Having two datatables hits the database twice(detached, doesn't lock data), so would it be better to just hit the database for the bulk table, then create a dataview from that and use it for the grid view? Would that decrease overhead or would it even be noticable?

I'm a bit new to c# and ado, so any input is appreciated.

Michael

I had several projects where I used the Schema Editor in VS to create the relationships. Then used the DataSet Generator to produce a "typed" DataSet. With a "typed" DataSet you get a parent-child Object Model.

I would not claim it is a perfect solution but for my needs in those projects it greatly simplified the data access development of the system.

As a note: those projects were in VS2003 and I have not yet worked with those tools in VS2005.

led mike

I'll look into that. Thanks

Michael

Here is my solution

gridRow = adminResults.Rows[adminResults.CurrentRow.Index];
String key =
gridRow.Cells["Username"].FormattedValue.ToString().Trim();

dataRows = dataTable.Select("USER_NAME = '" + key + "'");

Hope this helps anyone else.

Michael

I wanted to perform a one-time validation when my DataGridView is first loaded and displayed. My PopulateControl() method, however, seems to set row.ErrorText too soon, as no error icons appear.

Moving it to the RowPrePaint event is fine as long as I know when I'm done completely processing all row paint events so that I can safely clear my InInitializeState when all procesing is done.

So besides the RowPrePaint event .. is there one final event that control puts out that I can listen for to know that I'm done initializing my DataGridView???

Thanks

You should be able to use this[^] to find out.

led mike

Greetings:

I am working my way through the MCSD "Developing Windows Based Apps" book. I'm in the section on databases and ADO. This chapter is woefully lacking in working examples so I am trying to contrive my own in order to see some of this stuff in action. To do this, I am connecting to the Northwind database supplied with Access in order to have a database to play with.

OK, so I have successfully connected to Northwind, I have used data readers and data adaptors to load tables from Northwind into data sets. I have successfully displayed the data using data grids. I have also successfully executed non querys, scalars and readers. Eveything is going tickety-boo.

However, the last thing on my agenda before moving on is to ADD a row to one of the tables and then actually write it back to the Northwind database file. To do this, I have fashioned a simple input form and when I get all the required input fields, I return from the form and execute the following:

		<br />
private void btnAddSupplier_Click(object sender, System.EventArgs e)<br />
{<br />
	AddSupplier	frmAdd = new AddSupplier();<br />
	frmAdd.ShowDialog( this );<br />
<br />
	if (frmAdd.AddSelected == false)<br />
		return;<br />
<br />
	oleDbDataAdapter_Suppliers.Fill( dataSet_Suppliers );<br />
<br />
	DataRow dr = dataSet_Suppliers.Tables[0].NewRow();<br />
	dr["SupplierID"] = System.DBNull.Value;<br />
	dr["CompanyName"] = frmAdd.CompanyName;<br />
	dr["ContactName"] = frmAdd.ContactName;<br />
	dr["ContactTitle"] = frmAdd.ContactTitle;<br />
	dr["Address"] = frmAdd.Address;<br />
	dr["Region"] = frmAdd.City;<br />
	dr["City"] = frmAdd.RegionProv;<br />
	dr["PostalCode"] = frmAdd.Postal;<br />
	dr["Country"] = frmAdd.Country;<br />
	dr["Phone"] = "";<br />
	dr["FAX"] = "";<br />
	dr["HomePage"] = "";<br />
<br />
	oleDbDataAdapter_Suppliers.Update( dataSet_Suppliers );<br />
	dataSet_Suppliers.Tables[0].Rows.Add( dr );<br />
	dr.AcceptChanges();<br />
}<br />

"dataSet_Suppliers" and "oleDbDataAdaptor_Suppliers" are both members of the main form that I am using for my experimentation scaffold. I am certain that the adaptor and data set are successfully loaded with the Supplier table. I am able to Fill the supplier data set through the data adaptor and bind the data set to a data grid and display it.

The problem is that the above code does not write the new row to the database file. It appears unchanged. The code executes OK, but the changes are not applied to the file. I am confused about the order in which I should call "AcceptChanges" for the DataRow and "Update" for the data adaptor. The MCSD book says that you must call "Update" on the data adaptor FIRST. I don't quite get why this is so but I have fooled around with the order and it doesn't make any difference. There is no change to the database file.

I am obviously a novice so I am assuming that I am missing a step somewhere. Any help would be appreciated.
Thank you,
Mark

Add before update?

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Is that a question or a suggestion?
M.

Suggestion but untested one. The ? absolves me of responsibility for it not working :p

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Hi Ennis:

I tried your suggestion. Now the lower part of my code block looks like this:

<br />
	dr["HomePage"] = "";<br />
	dataSet_Suppliers.Tables[0].Rows.Add( dr );<br />
	oleDbDataAdapter_Suppliers.Update( dataSet_Suppliers );<br />
	dr.AcceptChanges();<br />

The call to "Update" now throws an OleDbException.
Thanks for your help anyway. If you have any other thoughts, I'm all ears...
Mark

move accept up one line. BTW, what are the specifics of the exception.

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

try the following code...

DataRowView NewRow = DataSet.Tables[TableName].DefaultView.AddNew()
NewRow[ColumnName] = "";
NewRow.EndEdit();
DataAdapter.Update(DataSet, TableName);

bahaa

OK, so my code now looks like this:

<br />
	DataRowView drv = dataSet_Suppliers.Tables[0].DefaultView.AddNew();<br />
	drv["SupplierID"] = System.DBNull.Value;<br />
	... more field assignments here ...<br />
	drv["HomePage"] = "";<br />
	drv.EndEdit();<br />
	oleDbDataAdapter_Suppliers.Update( dataSet_Suppliers, "Suppliers" );<br />

When I call the "Update" command, an OleDbException is thrown.

Any other thoughts?
Mark

What the OleDbException message say...?

Hi Friend,
I want to build some controls for web.
Where to start?
I have built some controls for windows using visual studio but not for web.

Like i want to make a colour chooser which I want to run on web pages.?

Any help will be appriciated.
thanks

Naveed Kamboh

Try the ASP.NET forum. Smile | :)

Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Messianic Instrumentals (with audio)
The apostle Paul, modernly speaking: Epistles of Paul

Judah Himango

Thank you.

Naveed Kamboh

I try to use the Win32 function "LogonUser". But I always get "false".

I add a user in windows "myuser" and the password is "mypassword". The domain is "mydomain".

Then I use it like this :

LogonUser("myuser", "mydomain", "mypassword", LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref token);

But the return value is always false.

Are there any possibilities to check if user and password is ok ?

If you're just validating user credentials, LogonUser is not the function to use. See How To Validate User Credentials on Microsoft Operating Systems[^] for more information.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Thanks for the link.
Have you ever tried that function before ?
I'm trying it using:
Username = ""
Password = ""
Domain = ""
And..the return value is TRUE... Smile | :)

That means user is valid.

This means that the current user who is logged in is already logged in - imagine that!

Dave Kreskowiak
Microsoft MVP - Visual Basic

I am using fingerprint reader.
Need help to capture the image in my application from fingerprint reader.

What's the mechanism used to capture image in fingerprint reader. Does it scans the image?

You'll need the SDK from the manufacturer of the Fingerprint Reader. Without it, you're not going to get anywhere.

Dave Kreskowiak
Microsoft MVP - Visual Basic