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fetch -- fetch instance(s) from a cursor
fetch [ (forward
| backward ) ] [ ( number | all ) ] [in cursor_name]
Fetch
allows a user to retrieve instances from a cursor named cursor_name. The
number of instances retrieved is specified by number. If the number of
instances remaining in the cursor is less than number, then only those
available are fetched. Substituting the keyword all in place of a number
will cause all remaining instances in the cursor to be retrieved. Instances
may be fetched in both forward and backward directions. The default direction
is forward.
Updating data in a cursor is not supported by Postgres, because
mapping cursor updates back to base classes is impossible in general as
with view updates. Consequently, users must issue explicit replace commands
to update data.
Cursors may only be used inside of transaction blocks marked
by begin(l)
and end(l)
because the data that they store spans multiple
user queries.
--
--set up and use a cursor
--
begin
declare
mycursor cursor for
select * from pg-user;
--
--Fetch all the instances
available in the cursor FOO
--
fetch all in FOO;
--
--Fetch 5 instances
backward in the cursor FOO
--
fetch backward 5 in FOO;
--
--close
--
close foo;
end;
begin(l)
, end(l)
, close(l)
, move(l)
, select(l)
.
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