The ADD DBEFILE statement updates a row in SYSTEM.DBEFile to show the 
DBEFileSet with which the file is associated.
Example | 
  | 
   CREATE DBEFILE ThisDBEFile WITH PAGES = 4,
                  NAME = 'ThisFile', TYPE = TABLE
   CREATE DBEFILESET Miscellaneous
   ADD DBEFILE ThisDBEFile TO DBEFILESET Miscellaneous
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The DBEFile is used to store rows of a new table. When the table needs an index, a DBEFile to store rows of the index is created: 
   CREATE DBEFILE ThatDBEFile WITH PAGES = 4,
                  NAME = 'ThatFile', TYPE = INDEX
   ADD DBEFILE ThatDBEFile TO DBEFILESET Miscellaneous
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When the index is subsequently dropped, its file space can be assigned to another DBEFileSet.
   REMOVE DBEFILE ThatDBEFile FROM DBEFILESET Miscellaneous
   ADD DBEFILE ThatDBEFile TO DBEFILESET SYSTEM
   ALTER DBEFILE ThisDBEFile SET TYPE = MIXED
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All rows are later deleted from the table, so you can reclaim file space.
   REMOVE DBEFILE ThisDBEFile FROM DBEFILESET Miscellaneous
   DROP DBEFILE ThisDBEFile
    The DBEFileSet definition can now be dropped. 
   DROP DBEFILESET Miscellaneous
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