ESRI ArcSDE (Spatial Database Engine) allows storage of GIS data (including feature geometry) in databases such as Microsoft SQL Server and Oracle. ArcSDE manages the storage of feature geometry using standard data types provided by the host database management system.
ArcSDE is part of the ArcGIS 9 system. ArcSDE manages the exchange of information between an (ArcGIS 9 Desktop) application and a relational database management system. FDO Provider for ArcSDE provides FDO with access to an ArcSDE 8.3-based data store, which, in this case, must be Oracle 9i.