SQL/MP Installation and Management Guide

Adding, Altering, Removing, and Renaming
Database Objects
HP NonStop SQL/MP Installation and Management Guide—523353-004
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Dropping Comments
Dropping Comments
You can drop comments at any time with no effect on the database. To drop
comments, use the COMMENT statement with the CLEAR option. The CLEAR option
drops all comments on the specified object.
This example drops all comments on a constraint on the DEPT table:
>> COMMENT ON CONSTRAINT MGRNUM_CONSTRAINT ON DEPT
+> IS "" CLEAR;
Purging SQL Objects and Enscribe Files
Use the PURGE command to delete a set of SQL objects and Enscribe files specified
in a qualified file set list. The PURGE command deletes the table or file and the
description in the catalog for SQL objects. PURGE also deletes dependent objects.
The results of a PURGE command are very similar to the results of a DROP statement.
If you want to purge only the data from an audited or nonaudited SQL table, use the
PURGEDATA command. This command deletes the data in the table and leaves the
table itself (the catalog description) intact. For more information about using
PURGEDATA, see Purging Data From SQL Tables on page 8-18.
Using DROP or PURGE
This list summarizes the differences between the operations of the DROP statement
and PURGE command:
•
PURGE allows many objects identified by a qualified file set list to be purged with
one command. The DROP statement drops one object at a time.
•
PURGE allows a file set list that contains both SQL objects and Enscribe files.
DROP operates only on SQL objects.
•
PURGE includes the ALLOWERRORS clause. If ALLOWERRORS is ON, the
command tries to purge the specified file set list regardless of the number of errors
that are encountered. If ALLOWERRORS is OFF or if you are using the DROP
statement, the first error encountered terminates the statement.
•
PURGE includes the LISTALL clause. If you specify LISTALL, you receive a
confirming message for each purged object. If you use the DROP statement or if
you omit the LISTALL option from the PURGE command, you receive no
confirming message about each purged object.
•
PURGE enables you to browse a selected file set list and select the objects to be
purged.
•
Both PURGE and DROP require the same security and authorization to purge or
drop objects.