mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-23 07:20:40 +02:00
71 lines
1.7 KiB
Plaintext
71 lines
1.7 KiB
Plaintext
.\" This is -*-nroff-*-
|
|
.\" XXX standard disclaimer belongs here....
|
|
.\" $Header: /cvsroot/pgsql/doc/man/Attic/fetch.l,v 1.2 1996/10/03 15:49:53 momjian Exp $
|
|
.TH FETCH SQL 01/23/93 Postgres95 Postgres95
|
|
.SH NAME
|
|
fetch \(em fetch instance(s) from a cursor
|
|
.SH SYNOPSIS
|
|
.nf
|
|
\fBfetch\fR [ (\fBforward\fR | \fBbackward\fR) ] [ ( number | \fBall\fR) ] [\fBin\fR cursor_name]
|
|
.fi
|
|
.SH DESCRIPTION
|
|
.BR Fetch
|
|
allows a user to retrieve instances from a cursor named
|
|
.IR cursor_name.
|
|
The number of instances retrieved is specified by
|
|
.IR number .
|
|
If the number of instances remaining in the cursor is less than
|
|
.IR number ,
|
|
then only those available are fetched. Substituting the keyword
|
|
.IR all
|
|
in place of a number will cause all remaining instances in the cursor
|
|
to be retrieved. Instances may be fetched in both
|
|
.IR forward
|
|
and
|
|
.IR backward
|
|
directions. The default direction is
|
|
.IR forward .
|
|
.PP
|
|
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.
|
|
.PP
|
|
Cursors may only be used inside of transaction blocks marked by
|
|
.IR begin (l)
|
|
and
|
|
.IR end (l)
|
|
because the data that they store spans multiple user queries.
|
|
.SH EXAMPLE
|
|
.nf
|
|
--
|
|
--set up and use a cursor
|
|
--
|
|
begin
|
|
declare mycursor cursor for
|
|
select * from pg-user
|
|
end
|
|
.fi
|
|
.nf
|
|
--
|
|
--Fetch all the instances available in the cursor FOO
|
|
--
|
|
fetch all in FOO
|
|
.fi
|
|
.nf
|
|
--
|
|
--Fetch 5 instances backward in the cursor FOO
|
|
--
|
|
fetch backward 5 in FOO
|
|
.fi
|
|
.SH "SEE ALSO"
|
|
begin(l),
|
|
end(l),
|
|
close(l),
|
|
move(l),
|
|
select(l).
|
|
.SH BUGS
|
|
Currently, the smallest transaction in Postgres is a single SQL
|
|
command. It should be possible for a single fetch to be a
|
|
transaction.
|