1 12/20/86 delete_attribute, dla
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 3 
 4 Syntax:  dla {attribute_name1 {...attribute_nameN} {-control_args}
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 6 
 7 Function:  This request deletes referenced or unreferenced attributes
 8 from a MRDS data base.
 9 
10 
11 Arguments:
12 attribute_namei
13    is the name of the attribute(s) to be deleted from the MRDS data
14    base.
15 
16 
17 Control arguments:
18 -all, -a
19    deletes all attributes defined in the MRDS data base.  This control
20    argument is inconsistent with -check.
21 -brief, -bf
22    suppresses the -long display.  (Default) The last occurrence of
23    -brief and -long on the command line takes effect.
24 -check, -ck
25    prevents the deletion of any attributes selected during the
26    execution of this command and, instead, traces all implied
27    operations upon the data base and displays them on the terminal.
28    This trace consists of a statement for each attribute that is
29    referenced, listing the relations that reference the attribute.
30 
31 
32 -force, -fc
33    prevents the query from being issued if any of the attributes are
34    referenced in the MRDS data base.  (Default is to issue a separate
35    query for each referenced attribute.)
36 -inhibit_error, -ihe
37    prevents error messages from being issued to the terminal.  (Default
38    is to issue error messages.)
39 -long, -lg
40    displays the same output as -check; however, the specified
41    attributes are deleted.
42 -no_force, -nfc
43    overrides the -force control argument.  The last occurrence of
44    -force and -no_force on the request line takes effect.  (Default)
45 -no_inhibit_error, -nihe
46    overrides the action of -inhibit_error.  (Default)
47 
48 
49 -unreferenced, -unref
50    deletes only unreferenced attributes.  This control argument
51    overrides -all and is inconsistent with -check.
52 
53 
54 Notes:  If an attribute is referenced in one or more relations, ripple
55 effects take place.  When the attributes are actually deleted, all
56 relations that use the deleted attributes are reformatted.
57 
58 
59 Specifying either -all or -unreferenced and a list of domain names on
60 the request line is flagged as an inconsistent error.
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62 
63 A query is issued for each referenced attribute that is to be deleted
64 to ensure against catastrophic data loss.  With the -long control
65 argument, the query is of the form:
66 
67 
68      Attribute "start_date" is used in relations "permanent_employees"
69      and "temporary_employees".  Do you wish to delete the attribute
70      start_date?
71