First of all,
Sorry for the delay in reply [ As I was out of station ]
The actual problem was data adapter need to be instantiated again for every when the query is changed. i.e. I just changed as below
da = New OleDbDataAdapter(wsql_query, con)
da.Fill(ds, "table2")
That's it, it is working fine.
But, As Amit told, it would be better to put it in procedure so that every thing gets done in one trip.
Thanks Again Amit for your suggestion and links provided.
Cheers
Anand