Sophie

Sophie

distrib > Mandriva > 2008.1 > x86_64 > media > main-testing > by-pkgid > bab02a23fa9f3df8d66a9a3231b50245 > files > 409

postgresql8.3-docs-8.3.6-2mdv2008.1.x86_64.rpm

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>PL/Perl Triggers</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 8.3.6 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="PL/Perl - Perl Procedural Language"
HREF="plperl.html"><LINK
REL="PREVIOUS"
TITLE="Trusted and Untrusted PL/Perl"
HREF="plperl-trusted.html"><LINK
REL="NEXT"
TITLE="Limitations and Missing Features"
HREF="plperl-missing.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2009-02-03T04:34:16"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
>PostgreSQL 8.3.6 Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="plperl-trusted.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="plperl.html"
>Fast Backward</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 40. PL/Perl - Perl Procedural Language</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="plperl.html"
>Fast Forward</A
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="plperl-missing.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PLPERL-TRIGGERS"
>40.6. PL/Perl Triggers</A
></H1
><P
>   PL/Perl can be used to write trigger functions.  In a trigger function,
   the hash reference <TT
CLASS="VARNAME"
>$_TD</TT
> contains information about the
   current trigger event. <TT
CLASS="VARNAME"
>$_TD</TT
> is a global variable, 
   which gets a separate local value for each invocation of the trigger. 
   The fields of the <TT
CLASS="VARNAME"
>$_TD</TT
> hash reference are:

   <P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{new}{foo}</TT
></DT
><DD
><P
>       <TT
CLASS="LITERAL"
>NEW</TT
> value of column <TT
CLASS="LITERAL"
>foo</TT
>
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{old}{foo}</TT
></DT
><DD
><P
>       <TT
CLASS="LITERAL"
>OLD</TT
> value of column <TT
CLASS="LITERAL"
>foo</TT
>
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{name}</TT
></DT
><DD
><P
>       Name of the trigger being called
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{event}</TT
></DT
><DD
><P
>       Trigger event: <TT
CLASS="LITERAL"
>INSERT</TT
>, <TT
CLASS="LITERAL"
>UPDATE</TT
>, <TT
CLASS="LITERAL"
>DELETE</TT
>, or <TT
CLASS="LITERAL"
>UNKNOWN</TT
>
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{when}</TT
></DT
><DD
><P
>       When the trigger was called: <TT
CLASS="LITERAL"
>BEFORE</TT
>, <TT
CLASS="LITERAL"
>AFTER</TT
>, or <TT
CLASS="LITERAL"
>UNKNOWN</TT
>
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{level}</TT
></DT
><DD
><P
>       The trigger level: <TT
CLASS="LITERAL"
>ROW</TT
>, <TT
CLASS="LITERAL"
>STATEMENT</TT
>, or <TT
CLASS="LITERAL"
>UNKNOWN</TT
>
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{relid}</TT
></DT
><DD
><P
>       OID of the table on which the trigger fired
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{table_name}</TT
></DT
><DD
><P
>       Name of the table on which the trigger fired
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{relname}</TT
></DT
><DD
><P
>       Name of the table on which the trigger fired. This has been deprecated,
       and could be removed in a future release. 
       Please use $_TD-&gt;{table_name} instead.
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{table_schema}</TT
></DT
><DD
><P
>       Name of the schema in which the table on which the trigger fired, is
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>$_TD-&gt;{argc}</TT
></DT
><DD
><P
>       Number of arguments of the trigger function
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>@{$_TD-&gt;{args}}</TT
></DT
><DD
><P
>       Arguments of the trigger function.  Does not exist if <TT
CLASS="LITERAL"
>$_TD-&gt;{argc}</TT
> is 0.
      </P
></DD
></DL
></DIV
><P>
  </P
><P
>   Triggers can return one of the following:

   <P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>return;</TT
></DT
><DD
><P
>       Execute the statement
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>"SKIP"</TT
></DT
><DD
><P
>       Don't execute the statement
      </P
></DD
><DT
><TT
CLASS="LITERAL"
>"MODIFY"</TT
></DT
><DD
><P
>       Indicates that the <TT
CLASS="LITERAL"
>NEW</TT
> row was modified by
       the trigger function
      </P
></DD
></DL
></DIV
><P>
  </P
><P
>   Here is an example of a trigger function, illustrating some of the
   above:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE TABLE test (
    i int,
    v varchar
);

CREATE OR REPLACE FUNCTION valid_id() RETURNS trigger AS $$
    if (($_TD-&gt;{new}{i} &gt;= 100) || ($_TD-&gt;{new}{i} &lt;= 0)) {
        return "SKIP";    # skip INSERT/UPDATE command
    } elsif ($_TD-&gt;{new}{v} ne "immortal") {
        $_TD-&gt;{new}{v} .= "(modified by trigger)";
        return "MODIFY";  # modify row and execute INSERT/UPDATE command
    } else {
        return;           # execute INSERT/UPDATE command
    }
$$ LANGUAGE plperl;

CREATE TRIGGER test_valid_id_trig
    BEFORE INSERT OR UPDATE ON test
    FOR EACH ROW EXECUTE PROCEDURE valid_id();</PRE
><P>
  </P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="plperl-trusted.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="plperl-missing.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Trusted and Untrusted PL/Perl</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="plperl.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Limitations and Missing Features</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>

Perl :: Catalyst :: PostgreSQL :: RPM Valid HTML 4.01 Transitional