RDBPROD: How to Use RMU/UNLOAD and /LOAD with AUTOMATIC and COMPUTED BY Columns
(Doc ID 237743.1)
Last updated on FEBRUARY 04, 2022
Oracle Rdb Server on OpenVMS - Version 7.1 and later HP OpenVMS Itanium HP OpenVMS Alpha
Oracle Rdb database columns with the AUTOMATIC or COMPUTED BY attributes are special columns whose values are calculated from other values, functions or constants. You are not permitted to INSERT or UPDATE the values in these columns.
The COMPUTED BY attribute specifies that the value of the column is computed automatically when the column is selected. There is no value stored in the database column. The value is computed for display or return to the application by the query.
The AUTOMATIC attribute allows Oracle Rdb to store special information on INSERT, UPDATE or both. The column data value is stored like other columns, but it is read-only. It must not appear in the column list for an INSERT operation nor be modified by an UPDATE operation. The AUTOMATIC attribute was introduced in Oracle Rdb 7.1.
The purpose of this article is to explain how to use RMU/UNLOAD and /LOAD with Oracle Rdb tables which include AUTOMATIC or COMPUTED BY columns.
NOTE: Derived fields use the COMPUTED BY clause in their definition. Views that contain UNION, GROUP BY, CASE and subqueries use derived fields. Therefore this article is also applicable to unloading views.
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