1. A database management system supporting nested invocation of user-defined routines and the definition of cursors, and the system carrying out execution steps in response to requests received from applications and from user-defined routines, the system comprising means for associating a unique identifier with each cursor occurrence request received by the system, the unique identifier including a first value corresponding to the nesting level of the source process from which the request originated, and a second value uniquely identifying the source process, relative to other sources at the same nesting level; and means for passing the unique identifier to the requesting process in response to the cursor occurrence request.