<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.29 2001/05/08 02:53:24 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.30 2001/05/11 06:10:44 tgl Exp $
-->
<chapter id="plpgsql">
</sect3>
<sect3 id="plpgsql-description-passed-vars">
- <title>Variables Passed to Functions</title>
+ <title>Parameters Passed to Functions</title>
<para>
- Variables passed to functions are named with the identifiers
+ Parameters passed to functions are named with the identifiers
<literal>$1</literal>, <literal>$2</literal>,
- etc. (maximum is 16). Some examples:
+ etc. Optionally, aliases can be declared for the <literal>$n</literal>
+ parameter names for increased readability. Some examples:
<programlisting>
CREATE FUNCTION sales_tax(REAL) RETURNS REAL AS '
DECLARE
<variablelist>
<varlistentry>
<term>
- %TYPE
+ <replaceable>variable</replaceable>%TYPE
</term>
<listitem>
<para>
values. For example, let's say you have a column
named <type>user_id</type> in your
<type>users</type> table. To declare a variable with
- the same datatype as users you do:
+ the same datatype as users.user_id you write:
<programlisting>
-user_id users.user_id%TYPE;
+user_id users.user_id%TYPE;
</programlisting>
</para>
<varlistentry>
<term>
- <replaceable>name</replaceable> <replaceable>table</replaceable>%ROWTYPE;
+ <replaceable>table</replaceable>%ROWTYPE
</term>
<listitem>
<para>
- Declares a row with the structure of the given
- table. <replaceable>table</replaceable> must be an existing
+ <type>%ROWTYPE</type> provides the composite datatype corresponding
+ to a whole row of the specified table.
+ <replaceable>table</replaceable> must be an existing
table or view name of the database. The fields of the row are
accessed in the dot notation. Parameters to a function can be
composite types (complete table rows). In that case, the
- corresponding identifier $n will be a rowtype, but it must be
- aliased using the ALIAS command described above.
+ corresponding identifier $n will be a rowtype, and fields can
+ be selected from it, for example <literal>$1.user_id</literal>.
</para>
<para>
- Only the user attributes of a table row are accessible in the
- row, no OID or other system attributes (because the row could
- be from a view). The fields of the rowtype inherit the
+ Only the user-defined attributes of a table row are accessible in a
+ rowtype variable, not OID or other system attributes (because the
+ row could be from a view). The fields of the rowtype inherit the
table's field sizes or precision for <type>char()</type>
etc. data types.
</para>
<programlisting>
DECLARE
users_rec users%ROWTYPE;
- user_id users%TYPE;
+ user_id users.user_id%TYPE;
BEGIN
user_id := users_rec.user_id;
...