71 lines
1.7 KiB
Plaintext
71 lines
1.7 KiB
Plaintext
.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/doc/man/Attic/fetch.l,v 1.1.1.1 1996/08/18 22:14:24 scrappy Exp $
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.TH FETCH SQL 01/23/93 Postgres95 Postgres95
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.SH NAME
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fetch \(em fetch instance(s) from a cursor
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.SH SYNOPSIS
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.nf
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\fBfetch\fR [ (\fBforward\fR | \fBbackward\fR) ] [ ( number | \fBall\fR) ] [\fBin\fR cursor_name]
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.fi
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.SH DESCRIPTION
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.BR Fetch
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allows a user to retrieve instances from a cursor named
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.IR cursor_name.
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The number of instances retrieved is specified by
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.IR number .
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If the number of instances remaining in the cursor is less than
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.IR number ,
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then only those available are fetched. Substituting the keyword
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.IR all
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in place of a number will cause all remaining instances in the cursor
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to be retrieved. Instances may be fetched in both
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.IR forward
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and
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.IR backward
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directions. The default direction is
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.IR forward .
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.PP
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Updating data in a cursor is not supported by Postgres, because mapping
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cursor updates back to base classes is impossible in general as with
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view updates. Consequently, users must issue explicit replace
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commands to update data.
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.PP
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Portals may only be used inside of transaction blocks marked by
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.IR begin (l)
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and
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.IR end (l)
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because the data that they store spans multiple user queries.
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.SH EXAMPLE
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.nf
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--
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--set up and use a cursor
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--
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begin
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declare myportal cursor for
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select * from pg-user
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end
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.fi
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.nf
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--
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--Fetch all the instances available in the portal FOO
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--
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fetch all in FOO
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.fi
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.nf
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--
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--Fetch 5 instances backward in the portal FOO
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--
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fetch backward 5 in FOO
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.fi
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.SH "SEE ALSO"
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begin(l),
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end(l),
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close(l),
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move(l),
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select(l).
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.SH BUGS
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Currently, the smallest transaction in Postgres is a single SQL
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command. It should be possible for a single fetch to be a
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transaction.
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