rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Update man page to prefer old over current.

This commit is contained in:
Bruce Momjian 2000-04-12 20:07:13 +00:00
parent 52f77df613
commit 2a08204e1f
1 changed files with 12 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
doc/src/sgml/ref/create_rule.sgml
View File

@ -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
-->
@ -71,7 +71,7 @@ CREATE RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable
<listitem>
<para>
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.
</para>
</listitem>
@ -81,7 +81,7 @@ CREATE RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable
<listitem>
<para>
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.
</para>
</listitem>
@ -133,17 +133,17 @@ CREATE
<para>
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
updates).
If the <replaceable class="parameter">event</replaceable>
specified in the ON clause and 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
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
<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>.
</para>
@ -167,7 +167,7 @@ CREATE
<replaceable class="parameter">condition</replaceable> and
<replaceable class="parameter">action</replaceable> parts of a rule,
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
two rules have the same semantics:
<programlisting>
@ -263,7 +263,7 @@ SELECT * FROM emp;
<programlisting>
CREATE RULE example_1 AS
ON UPDATE emp.salary WHERE current.name = "Joe"
ON UPDATE emp.salary WHERE old.name = "Joe"
DO
UPDATE emp
SET salary = new.salary
@ -271,7 +271,7 @@ CREATE RULE example_1 AS
</programlisting>
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.
Hence, his new salary is substituted into the action part
of the rule which is subsequently executed. This propagates
@ -282,7 +282,7 @@ CREATE RULE example_1 AS
<programlisting>
CREATE RULE example_2 AS
ON SELECT TO EMP.salary
WHERE current.name = "Bill"
WHERE old.name = "Bill"
DO INSTEAD
SELECT emp.salary
FROM emp
@ -297,7 +297,7 @@ CREATE RULE example_2 AS
CREATE RULE example_3 AS
ON
SELECT TO emp.salary
WHERE current.dept = "shoe" AND current_user = "Joe"
WHERE old.dept = "shoe" AND current_user = "Joe"
DO INSTEAD NOTHING;
</programlisting>
</para>