From 455891bf96f6ee3dda9150fe83af2be5e86a572b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 3 Jul 2003 16:34:26 +0000
Subject: Code review for UPDATE tab SET col = DEFAULT patch ... whack it
 around so it has some chance of working in rules ...

---
 doc/src/sgml/ref/insert.sgml |  6 +++---
 doc/src/sgml/ref/update.sgml | 37 ++++++++++++++++++++++++++-----------
 2 files changed, 29 insertions(+), 14 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index d2e29a8757..cbb0d279bd 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/insert.sgml,v 1.22 2003/04/26 23:56:51 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/insert.sgml,v 1.23 2003/07/03 16:32:03 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -33,7 +33,7 @@ INSERT INTO <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable
   <para>
    The columns in the target list may be listed in any order.
    Each column not present in the target list will be inserted
-   using a default value, either a declared default value
+   using a default value, either its declared default value
    or null.
   </para>
 
@@ -77,7 +77,7 @@ INSERT INTO <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable
     <term><literal>DEFAULT VALUES</literal></term>
     <listitem>
      <para>
-      All columns will be filled their default values.
+      All columns will be filled with their default values.
      </para>
     </listitem>
    </varlistentry>
diff --git a/doc/src/sgml/ref/update.sgml b/doc/src/sgml/ref/update.sgml
index 02cc07b0bd..1fe85b995e 100644
--- a/doc/src/sgml/ref/update.sgml
+++ b/doc/src/sgml/ref/update.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/update.sgml,v 1.22 2003/06/25 04:19:24 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/update.sgml,v 1.23 2003/07/03 16:32:12 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -28,7 +28,8 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
   <para>
    <command>UPDATE</command> changes the values of the specified
    columns in all rows that satisfy the condition. Only the columns to
-   be modified need appear as columns in the statement.
+   be modified need be mentioned in the statement; columns not explicitly
+   <literal>SET</> retain their previous values.
   </para>
 
   <para>
@@ -41,8 +42,9 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
   <para>
    You must have the <literal>UPDATE</literal> privilege on the table
    to update it, as well as the <literal>SELECT</literal>
-   privilege to any table whose values are read in the <replaceable
-   class="parameter">condition</replaceable>.
+   privilege to any table whose values are read in the
+   <replaceable class="parameter">expression</replaceable>s or
+   <replaceable class="parameter">condition</replaceable>.
   </para>
  </refsect1>
 
@@ -72,7 +74,8 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
     <term><replaceable class="PARAMETER">expression</replaceable></term>
     <listitem>
      <para>
-      An expression or value to assign to the column.
+      An expression to assign to the column.  The expression may use the
+      old values of this and other columns in the table.
      </para>
     </listitem>
    </varlistentry>
@@ -81,7 +84,8 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
     <term><literal>DEFAULT</literal></term>
     <listitem>
      <para>
-      This column will be filled with its default value.
+      Set the column to its default value (which will be NULL if no
+      specific default expression has been assigned to it).
      </para>
     </listitem>
    </varlistentry>
@@ -91,7 +95,7 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
     <listitem>
      <para>
       A list of table expressions, allowing columns from other tables
-      to appear in the <literal>WHERE</> condition.
+      to appear in the <literal>WHERE</> condition and the update expressions.
      </para>
     </listitem>
    </varlistentry>
@@ -100,9 +104,9 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
     <term><replaceable class="PARAMETER">condition</replaceable></term>
     <listitem>
      <para>
-      A value expression that returns a value of type
-      <type>boolean</type> that determines the rows which are to be
-      updated.
+      An expression that returns a value of type <type>boolean</type>.
+      Only rows for which this expression returns <literal>true</>
+      will be updated.
      </para>
     </listitem>
    </varlistentry>
@@ -135,9 +139,20 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replacea
    column <structfield>kind</> of the table <literal>films</literal>:
 
 <programlisting>
-UPDATE filme SET kind = 'Dramatic' WHERE kind = 'Drama';
+UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
 </programlisting>
   </para>
+
+  <para>
+   Adjust temperature entries and reset precipitation to its default
+   value in one row of the table <literal>weather</literal>:
+
+<programlisting>
+UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
+  WHERE city = 'San Francisco' AND date = '2003-07-03';
+</programlisting>
+  </para>
+
  </refsect1>
 
  <refsect1>
-- 
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