What's going on in this ADO2 code

[phonl]

VB.NET 2005 and ADO2.NET

After years of VB6 and ADO coding, I'm checking out ADO2.NET.

I spent several hours trying to figure out why the line:
objDataAdapter.Update(objDataSet, "myTable")

caused this error:
Update requires a valid UpdateCommand when passed DataRow collection with
modified rows.

In this code:
objDataSet.Tables("myTable").Rows(1).EndEdit()
If objDataSet.HasChanges Then
objDataAdapter.Update(objDataSet, "myTable") <--error here
End If

After much Google, I found that adding this line solved the problem:
Dim cb As New OleDb.OleDbCommandBuilder(objDataAdapter)

So the working code is:
Dim cb As New OleDb.OleDbCommandBuilder(objDataAdapter)
objDataSet.Tables("myTable").Rows(1).EndEdit()
If objDataSet.HasChanges Then
objDataAdapter.Update(objDataSet, "myTable")
End If

What's going on here? What is "cb" doing to the DataAdapter?

 

[Marina Levit [MVP]]

It's generate the update/insert/delete commands so that the adapter knows
what queries to run.

You either need to set the InsertCommand, UpdateCommand, DeleteCommand
properties to call appropriate queries or stored procedures with all the
parameters set up correctly, or use the commandbuilder and have it do it for
you.

There are issues with both approaches, and there have been many discussions
on the subject in this newsgroup.

 

[Marina Levit [MVP]]

I meant to say the subject has been discussed many times in the adonet
newsgroup.

 

[Yuan Ren[MSFT]]

Hi Phonl,

Thanks for posting!

As Marina mentioned, the issue is caused when UpdateCommand isn't specified
for the DataAdapter. The following KB article demonstrates how to resolve
the problem when the error occurs:
http://support.microsoft.com/default.aspx?scid=kb;en-us;310376

In addition, I think the specification from MSDN give us more details about
the current issue:
http://msdn2.microsoft.com/en-us/library/a19c81fk.aspx

I hope this will be helpful!

Regards,

Yuan Ren [MSFT]
Microsoft Online Support
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