I'm working on my own implementation of an ADO.NET Data Provider
derived from IDbXXXX classes and MSDN sample
(http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconImplementingNETDataProvider.asp).
All is fine when I execute simple Command and DataReader but I got an
error with DataAdapter.
Running of SelectCmd and InsertCmd work fine but each UpdateCmd or
DeleteCmd thrown a DBConcurrencyException.
It seems that problem is that DataAdapter call ExecuteReader instead
of ExecuteNonQuery on InsertCmd, UpdateCmd and DeleteCmd. So, number
of row affected is probably incorrect.
Do I miss something or is it an usual way of working for a DataAdapter
?
Why ExecuteReader is called for an Update and a Delete without any
result expected ?
Thanks in advance for your help or advices.

               Lionel.

Hi Lionel,

I guess the reader part is because of concurrency issues (to load timestamp
or autoinc key).
See help on
IDbCommand.UpdatedRowSource Property

Show quoteHide quote

Thanks for your answer but my DataSet don't have any autoinc or timestamp
key and I have just one access on my table (local database).
I tried all enum value in System.Data.UpdateRowSource and I have the same
exception thrown: DBConcurrencyException.
I'm really wonder why for an UPDATE command DbDataAdapter.Update calls my
command with ExecuteReader instead of ExecuteNonQuery. Here is my source
code:


    // ... On init

    dataAdapter = new MyADOProvider.MyDataAdapter(selectCmd);
    dataAdapter.UpdateCommand = new MyADOProvider.MyCommand("MyProc
@action='UPDATE',", cnx);
    dataAdapter.UpdateCommand.CommandType = CommandType.StoredProcedure;
    param = dataAdapter.UpdateCommand.CreateParameter();
    param.DbType = DbType.Int32;
    param.ParameterName = "@code";
    dataAdapter.UpdateCommand.Parameters.Add(param);
    param = dataAdapter.UpdateCommand.CreateParameter();
    param.DbType = DbType.String;
    param.ParameterName = "@name";
    dataAdapter.UpdateCommand.Parameters.Add(param);

    dataSet = new DataSet();
    dataAdapter.Fill(dataSet, "results");


    //... On Update button

    dataAdapter.Update(dataSet, "results");

My guess is that with a ExecuteNonQuery, you can have a "Number of rows
affected" but you can't have this number with a ExecuteReader.
Is someone know the source code of DbDataAdapter.Update ?

                             Lionel.


eGMqrZx7EHA.2***@TK2MSFTNGP10.phx.gbl...
Show quoteHide quote

Hmm, I don't see any UpdateRowSource setting in your code.

Show quoteHide quoteSure, try with Reflector.
http://www.aisto.com/roeder/dotnet/

ebA$vX%237EHA.3***@TK2MSFTNGP15.phx.gbl...
Show quoteHide quoteOf course, I deleted it before publishing here. You can believe me : I made
the test :-)

Show quoteHide quoteWaaooo!!! Reflector is really a great tool but my first look on source code
for System.Data.Common.DbDataAdapter.Update give me more new questions than
anwser... :-(

Show quoteHide quote

Indeed :-)

but my first look on source code
Not trivial, eh-

Validating data.
Recordsets and Ref Cursors
DataReader and record locking problem
Connection pooling...
URGENT:Viewing MULTIPLE RECORDS from database using DATA READER