While this paper is dedicated to the integration with and migration of data from an AS/400 to SQL Server, this migration can happen in many forms or scenarios. The determination as to which of these scenarios should be used must be made after studying what data is needed on the SQL Server for decision support and how current that data must be. After determining what data is needed, the amount of that data will also play a role in what method and frequency is chosen for data migration.
If volumes and currency needs allow it, the simplest migration scenarios involve moving all data. This can also include performing summarization during the transfer to reduce the amount of data transferred.
If all of the data cannot be easily transferred, or if changes on the AS/400 need to be reflected in the SQL Server data more often than daily, a changed row strategy needs to be used. In this scenario, only the rows which have recently changed are migrated to the SQL Server. This type of transfer is considerably more involved than moving all data, but at times is necessary or highly desirable.