If 2 people edits the data in a dataset at the same time and updates the datasource, will the edit of the first person get overwritten.Please guide me.

you can control such errors through both dataset(including datatable) and your dataadapter.
i.e you can control in your datatable object through GetErrors() methode...
this method supposes the user has finished the updating(in discconected enviroment)the rows and provides you with a datarow array that includes rows have some errors(even you can use this methode in your complex datasets)
(this I told doesnt have any connection with your problem!!!)
also you can control your errors while updating your datasource through Update()
method in DataAdapter object,it has two events,RowUpdating and RowUpdated...
RowUpdating occurs while updating your datasource but RowUpdated occurs after that
this two events have their argument and through them you can continue or stop updating your datasource according to probable errors
for example RowUpdating event gets an argument called RowUpdatingEventArgs,then you can use this and determine if there were errors(with Errors property) and.....
for more information have a look at MSDN.
HTH.

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Mehdi.:)

Hello,

Without any coding to see if the original values match what's in the database, by default yes, if both update at the same time, the data source should implement transactions where the first person accesses the table, then the second person does.

That's the transaction model. Is that what you wanted to know, or am I completely off?

Brian