Symptoms
When you use DataReader to read a row, if you try to access columns in that row, you receive an error message similar to the following:

System.InvalidOperationException: Invalid attempt to read from column ordinal ‘0′.With CommandBehavior.SequentialAccess, you may only read from column ordinal ‘2′ or greater.
Resolution
This problem occurs because you executed OleDbCommand or SqlCommand with the System.Data.CommandBehavior.SequentialAccess flag set but did not access the columns sequentially.