There are several operations that affect SYSTABLES and SYSVOLUMES:
When a volume is attached, its information is added to SYSVOLUMES;
When a table is attached, including if it is attached as part of attaching a volume, its information is added to SYSTABLES and the table name is added to the list in field 3 of the appropriate SYSVOLUMES record;
When a volume is detached, its information is removed from SYSVOLUMES, and all of its tables are detached;
When a table is detached, its information is removed from SYSTABLES and the table name is removed from the list in field 3 of the appropriate SYSVOLUMES record;
When a table is opened, the handle returned from its filing systems is stored in field 5 of SYSTABLES; note that subsequent opens of the table (after field 5 is filled in) do not actually do anything (i.e. they do not call the filing system).
If a SYSTABLES record refers to a volume (field 1) that does not exist or that does not refer back (field 3) to the table, or if a SYSVOLUMES record refers to a table (field 3) that does not exist or that does not refer back to the volume, then the database is unsynchronized. OpenInsight automatically corrects problems such as this one by checking the integrity of the SYSVOLUMES and SYSTABLES data when a .DBT file is loaded and before a .DBT file is saved. For more information, see Problems with DBT Files, and Synchronizing the Volume and Table Information.
To manually synchronize the database with the .DBT file, perform a Database Save operation from the Database Manager. This will save any database changes to the application's .DBT file. From BASIC+, the Define Database subroutine synchronizes the database. OpenInsight automatically synchronizes the database when you log off.
After attaching the REVMEDIA table for a volume, compare fields 4 and 5 of the SYSTABLES record for REVMEDIA with fields 4 and 5 of the SYSVOLUMES record for the volume for which REVMEDIA was attached.
