
UNDO
Restores
the
previous
select
le.
Syntax
UN
2
DO
3
Discussion
The
UNDO
command
clears
the
last
SUBSET
retriev
al
and
returns
y
ou
to
the
previous
lev
el
of
data
retriev
al.
Eac
h
group
of
retrieved
en
tries
is
stored
in
a
temp orary
in
ternal
le
kno
wn
as
a
select
le.
En
tering
the
UNDO
command
remov
es
the
last
group
of
retrieved
en
tries
(select
le)
and
restores
the
previous
group
of
retrieved
en
tries
as
the
curren
t
select
le.
The
restored
select
le
can
b e
the
result
of
a
previous
SUBSET,
FIND,
or
MUL
TIFIND
command,
but
UNDO
m
ust
follow
a
SUBSET
command.
After
eac
h
SUBSET
retriev
al,
QUER
Y
prin
ts
the
n
um
b er
of
qualied
en
tries
retrieved.
Examples
Example
1
-->
> FIND
ALL
PERIODICAL.JOURNAL
|
USING
SERIAL
READ
|
60
ENTRIES
QUALIFIED
|
> SUBSET
PERIODICAL.JOURNAL
=
CALIFORNIA
|
30
ENTRIES
QUALIFIED
--
> UNDO
In
this
example,
the
previous
60
en
tries
are
in
the
curren
t
select
le
again.
Example
2
> FIND
ALL
PERIODICAL.JOURNAL
USING
SERIAL
READ
60
ENTRIES
QUALIFIED
-->
> SUBSET
PERIODICAL.JOURNAL
=
CALIFORNIA
|
30
ENTRIES
QUALIFIED
|
> SUBSET
PERIODICAL.YEAR
=
85
|
10
ENTRIES
QUALIFIED
---
> UNDO
In
example
2,
the
previous
30
en
tries
are
in
the
curren
t
select
le
again.
3-146
QUERY/V
COMMANDS
Summary of Contents for QUERY
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Page 17: ...Figure 1 1 ORDERS Data Base Structure Figure 1 2 Sample Entry Values INTRODUCING QUERY V 1 7 ...
Page 20: ...Figure 1 3 IMAGE QUERY Environments 1 10 INTRODUCING QUERY V ...
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Page 165: ...REPORT G1 GROUP TITLE 11 END QUERY V COMMANDS 3 129 ...
Page 199: ...XEQ TF TOTAL DUE 9 SPACE B2 SKIP A TF R0 70 E2 S PURCH DATE END QUERY V COMMANDS 3 163 ...
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Page 279: ...G ASCII CHARACTER SET This appendix is not available in this edition ASCII CHARACTER SET G 1 ...
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