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Update man page to prefer old over current.

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Bruce Momjian 2000-04-12 20:07:13 +00:00
parent 52f77df613
commit 2a08204e1f
1 changed files with 12 additions and 12 deletions
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24
doc/src/sgml/ref/create_rule.sgml
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@ -1,5 +1,5 @@
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.14 2000/04/07 19:17:30 momjian Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.15 2000/04/12 20:07:13 momjian Exp $
Postgres documentation Postgres documentation
--> -->
@ -71,7 +71,7 @@ CREATE RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable
<listitem> <listitem>
<para> <para>
Any SQL WHERE clause, <literal>new</literal> or Any SQL WHERE clause, <literal>new</literal> or
<literal>current</literal> can appear instead of an instance <literal>old</literal> can appear instead of an instance
variable whenever an instance variable is permissible in SQL. variable whenever an instance variable is permissible in SQL.
</para> </para>
</listitem> </listitem>
@ -81,7 +81,7 @@ CREATE RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable
<listitem> <listitem>
<para> <para>
Any SQL statement, <literal>new</literal> or Any SQL statement, <literal>new</literal> or
<literal>current</literal> can appear instead of an instance <literal>old</literal> can appear instead of an instance
variable whenever an instance variable is permissible in SQL. variable whenever an instance variable is permissible in SQL.
</para> </para>
</listitem> </listitem>
@ -133,17 +133,17 @@ CREATE
<para> <para>
The semantics of a rule is that at the time an individual instance is The semantics of a rule is that at the time an individual instance is
accessed, inserted, updated, or deleted, there is a current instance (for accessed, inserted, updated, or deleted, there is a old instance (for
selects, updates and deletes) and a new instance (for inserts and selects, updates and deletes) and a new instance (for inserts and
updates). updates).
If the <replaceable class="parameter">event</replaceable> If the <replaceable class="parameter">event</replaceable>
specified in the ON clause and the specified in the ON clause and the
<replaceable class="parameter">condition</replaceable> specified in the <replaceable class="parameter">condition</replaceable> specified in the
WHERE clause are true for the current instance, the WHERE clause are true for the old instance, the
<replaceable class="parameter">action</replaceable> part of the rule is <replaceable class="parameter">action</replaceable> part of the rule is
executed. First, however, values from fields in the current instance executed. First, however, values from fields in the old instance
and/or the new instance are substituted for and/or the new instance are substituted for
<literal>current.</literal><replaceable class="parameter">attribute-name</replaceable> <literal>old.</literal><replaceable class="parameter">attribute-name</replaceable>
and <literal>new.</literal><replaceable class="parameter">attribute-name</replaceable>. and <literal>new.</literal><replaceable class="parameter">attribute-name</replaceable>.
</para> </para>
@ -167,7 +167,7 @@ CREATE
<replaceable class="parameter">condition</replaceable> and <replaceable class="parameter">condition</replaceable> and
<replaceable class="parameter">action</replaceable> parts of a rule, <replaceable class="parameter">action</replaceable> parts of a rule,
they are all considered different tuple variables. More accurately, they are all considered different tuple variables. More accurately,
<literal>new</literal> and <literal>current</literal> are the only tuple <literal>new</literal> and <literal>old</literal> are the only tuple
variables that are shared between these clauses. For example, the following variables that are shared between these clauses. For example, the following
two rules have the same semantics: two rules have the same semantics:
<programlisting> <programlisting>
@ -263,7 +263,7 @@ SELECT * FROM emp;
<programlisting> <programlisting>
CREATE RULE example_1 AS CREATE RULE example_1 AS
ON UPDATE emp.salary WHERE current.name = "Joe" ON UPDATE emp.salary WHERE old.name = "Joe"
DO DO
UPDATE emp UPDATE emp
SET salary = new.salary SET salary = new.salary
@ -271,7 +271,7 @@ CREATE RULE example_1 AS
</programlisting> </programlisting>
At the time Joe receives a salary adjustment, the event At the time Joe receives a salary adjustment, the event
will become true and Joe's current instance and proposed will become true and Joe's old instance and proposed
new instance are available to the execution routines. new instance are available to the execution routines.
Hence, his new salary is substituted into the action part Hence, his new salary is substituted into the action part
of the rule which is subsequently executed. This propagates of the rule which is subsequently executed. This propagates
@ -282,7 +282,7 @@ CREATE RULE example_1 AS
<programlisting> <programlisting>
CREATE RULE example_2 AS CREATE RULE example_2 AS
ON SELECT TO EMP.salary ON SELECT TO EMP.salary
WHERE current.name = "Bill" WHERE old.name = "Bill"
DO INSTEAD DO INSTEAD
SELECT emp.salary SELECT emp.salary
FROM emp FROM emp
@ -297,7 +297,7 @@ CREATE RULE example_2 AS
CREATE RULE example_3 AS CREATE RULE example_3 AS
ON ON
SELECT TO emp.salary SELECT TO emp.salary
WHERE current.dept = "shoe" AND current_user = "Joe" WHERE old.dept = "shoe" AND current_user = "Joe"
DO INSTEAD NOTHING; DO INSTEAD NOTHING;
</programlisting> </programlisting>
</para> </para>