sequential invoice numbers?

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От will trillich
Тема sequential invoice numbers?
Дата
Msg-id 20020110112255.B27772@serensoft.com
обсуждение исходный текст
Список pgsql-general
Дерево обсуждения 
the serial datatype guarantees a unique id on every invocation
(nextval('table_field_seq')) but also warns there can be gaps in
the numbering sequence (after a begin/rollback for example).

is there a facility for guaranteeing sequential numbers, as for
invoicing? our accountant-type anal retentives seem to not like
gaps in the numbering. what's the elegant way to arrange that?

i'm thinking about something like this--

    CREATE FUNCTION this_id() RETURNS INTEGER AS '
        SELECT MAX(id) FROM sometable
    ' LANGUAGE 'sql';

    CREATE FUNCTION next_id() RETURNS INTEGER AS '
    DECLARE
        new_id INTEGER;
    BEGIN
        BEGIN;
        LOCK TABLE sometable EXCLUSIVE;
        new_id := 1 + this_id();
        INSERT INTO sometable(id) VALUES (new_id);
        COMMIT;
        RETURN new_id;
    END;
    ' LANGUAGE 'plpgsql';

    CREATE VIEW someview AS
    SELECT * FROM sometable;

    CREATE RULE add_id AS
    ON INSERT TO someview
    DO INSTEAD (
        UPDATE sometable SET
            f1 = NEW.f1,
            f2 = NEW.f2,
            fN = NEW.fN
        WHERE
            id = next_id() -- does the lock mess up the update?
        ;
    );

is this the paradigm to use with v7.1? maybe the lock belongs in
the rule, instead? or am i all wet?

--
DEBIAN NEWBIE TIP #100 from Leonard Stiles <ljs@uk2.net>
:
Looking for a way to CREATE A PAGE OF LINKS to all the
*/index.html that already exist in your /usr/share/doc tree?
    #!/bin/sh
    # as /usr/doc contains lots of symlinks to /usr/share/doc, adding
    # -follow to find args may be useful.
    { echo '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"'
      echo '"http://www.w3.org/TR/html40/strict.dtd">';
      echo '<html><head><title>Documentation Links</title></head><body>';
      find /usr/doc -name index.html \
           -printf '<href="file:%p">%P</a><br>\n';
      echo '</body></html>';
    } > links.html

Also see http://newbieDoc.sourceForge.net/ ...

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