12/20/86 delete_attribute, dla


Syntax:  dla {attribute_name1 {...attribute_nameN} {-control_args}


Function:  This request deletes referenced or unreferenced attributes
from a MRDS data base.


Arguments:
attribute_namei
   is the name of the attribute(s) to be deleted from the MRDS data
   base.


Control arguments:
-all, -a
   deletes all attributes defined in the MRDS data base.  This control
   argument is inconsistent with -check.
-brief, -bf
   suppresses the -long display.  (Default) The last occurrence of
   -brief and -long on the command line takes effect.
-check, -ck
   prevents the deletion of any attributes selected during the
   execution of this command and, instead, traces all implied
   operations upon the data base and displays them on the terminal.
   This trace consists of a statement for each attribute that is
   referenced, listing the relations that reference the attribute.


-force, -fc
   prevents the query from being issued if any of the attributes are
   referenced in the MRDS data base.  (Default is to issue a separate
   query for each referenced attribute.)
-inhibit_error, -ihe
   prevents error messages from being issued to the terminal.  (Default
   is to issue error messages.)
-long, -lg
   displays the same output as -check; however, the specified
   attributes are deleted.
-no_force, -nfc
   overrides the -force control argument.  The last occurrence of
   -force and -no_force on the request line takes effect.  (Default)
-no_inhibit_error, -nihe
   overrides the action of -inhibit_error.  (Default)


-unreferenced, -unref
   deletes only unreferenced attributes.  This control argument
   overrides -all and is inconsistent with -check.


Notes:  If an attribute is referenced in one or more relations, ripple
effects take place.  When the attributes are actually deleted, all
relations that use the deleted attributes are reformatted.


Specifying either -all or -unreferenced and a list of domain names on
the request line is flagged as an inconsistent error.


A query is issued for each referenced attribute that is to be deleted
to ensure against catastrophic data loss.  With the -long control
argument, the query is of the form:


     Attribute "start_date" is used in relations "permanent_employees"
     and "temporary_employees".  Do you wish to delete the attribute
     start_date?



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Historical Background

This edition of the Multics software materials and documentation is provided and donated
to Massachusetts Institute of Technology by Group BULL including BULL HN Information Systems Inc. 
as a contribution to computer science knowledge.  
This donation is made also to give evidence of the common contributions of Massachusetts Institute of Technology,
Bell Laboratories, General Electric, Honeywell Information Systems Inc., Honeywell BULL Inc., Groupe BULL
and BULL HN Information Systems Inc. to the development of this operating system. 
Multics development was initiated by Massachusetts Institute of Technology Project MAC (1963-1970),
renamed the MIT Laboratory for Computer Science and Artificial Intelligence in the mid 1970s, under the leadership
of Professor Fernando Jose Corbato. Users consider that Multics provided the best software architecture 
for managing computer hardware properly and for executing programs. Many subsequent operating systems 
incorporated Multics principles.
Multics was distributed in 1975 to 2000 by Group Bull in Europe , and in the U.S. by Bull HN Information Systems Inc., 
as successor in interest by change in name only to Honeywell Bull Inc. and Honeywell Information Systems Inc. .

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Permission to use, copy, modify, and distribute these programs and their documentation for any purpose and without
fee is hereby granted,provided that the below copyright notice and historical background appear in all copies
and that both the copyright notice and historical background and this permission notice appear in supporting
documentation, and that the names of MIT, HIS, BULL or BULL HN not be used in advertising or publicity pertaining
to distribution of the programs without specific prior written permission.
    Copyright 1972 by Massachusetts Institute of Technology and Honeywell Information Systems Inc.
    Copyright 2006 by BULL HN Information Systems Inc.
    Copyright 2006 by Bull SAS
    All Rights Reserved