Question : Export data from excel sheet to oracle

Hi Could anyone please help me with the update query. iam uploading data's from an access database to oracle table. here's my coding. please help me what would  be the update query if i want to update the existing data in the oracle table. here's the coding for loading the data's , but i want the update query . please help me.

 Dim xlconn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\db1.mdb")
            Dim xlda As New OleDbDataAdapter("select * from sheet1", xlconn)
            Dim xldt As New DataTable
            xlda.Fill(xldt)
            xlda.Dispose()
            xlconn.Close()

            Dim conn As New OracleClient.OracleConnection("Data Source=PRICING_DATA;User ID=PRICING;Password=pr1c1ng")
            'Dim DR As OracleClient.OracleDataReader
            conn.Open()
            Dim cmd As OracleClient.OracleCommand = conn.CreateCommand

            cmd.CommandText = "SELECT * FROM test_erp_crossreference"
            cmd.ExecuteNonQuery()
                 
            Dim da As New OracleClient.OracleDataAdapter(cmd)
            Dim cb As OracleClient.OracleCommandBuilder = New OracleClient.OracleCommandBuilder(da)
            Dim ds As New DataSet
            da.Fill(ds, "test_erp_crossreference")

            For Each xlrow As DataRow In xldt.Rows
                Dim dr As DataRow = ds.Tables("test_erp_crossreference").NewRow
                For Each col As DataColumn In ds.Tables("test_erp_crossreference").Columns
                    dr(col.ColumnName) = xlrow(col.ColumnName)
                Next
                ds.Tables("test_erp_crossreference").Rows.Add(dr)
            Next

            da.Update(ds, "test_erp_crossreference")
            Response.Write("")

            da.Dispose()
            conn.Close()

Answer : Export data from excel sheet to oracle

select * from excel_table where product_key='somedata'
then get values for columns product_key abd product_no and update oracle table with their values