+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Slot Options</title>
+ <itemizedlist>
+ <listitem>
+ <para>
+ <parameter>:db-kind</parameter> - specifies the kind of
+ database mapping which is performed for this slot and defaults
+ to <parameter>:base</parameter> which indicates that the
+ slot maps to an ordinary column of the database table. A
+ <parameter>:db-kind</parameter> value of
+ <parameter>:key</parameter> indicates that this slot is
+ a special kind of <parameter>:base</parameter> slot
+ which maps onto a column which is one of the unique keys
+ for the database table, the value
+ <parameter>:join</parameter> indicates this slot
+ represents a join onto another View Class which contains
+ View Class objects, and the value
+ <parameter>:virtual</parameter> indicates a standard
+ CLOS slot which does not map onto columns of the
+ database table.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:db-info</parameter> - if a slot is specified with
+ <parameter>:db-kind</parameter> <parameter>:join</parameter>, the
+ slot option <parameter>:db-info</parameter> contains a property list
+ which specifies the nature of the join. The valid members of the list
+ are:
+ </para>
+ <itemizedlist>
+ <listitem>
+ <para>
+ <parameter>:join-class</parameter>
+ <emphasis>class-name</emphasis> - the name of the
+ class to join on.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:home-key</parameter>
+ <emphasis>slot-name</emphasis> - the name of the slot
+ of this class for joining
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:foreign-key</parameter>
+ <emphasis>slot-name</emphasis> - the name of the slot
+ of the <parameter>:join-class</parameter> for joining
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:target-slot</parameter>
+ <emphasis>target-slot</emphasis> - this is an optional
+ parameter. If specified, then the join slot of the
+ defining class will contain instances of this target
+ slot rather than of the join class. This can be useful
+ when the <parameter>:join-class</parameter> is an
+ intermediate class in a
+ <emphasis>many-to-many</emphasis> relationship and the
+ application is actually interested in the
+ <parameter>:target-slot</parameter>.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:retrieval</parameter>
+ <emphasis>time</emphasis> - The default value is
+ <parameter>:deferred</parameter>, which defers filling
+ this slot until the value is accessed. The other valid
+ value is <parameter>:immediate</parameter> which
+ performs the SQL query when the instance of the class
+ is created. In this case, the
+ <parameter>:set</parameter> is automatically set to
+ &nil;
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:set</parameter>
+ <emphasis>set</emphasis> - This controls what is stored in the join slot.
+ The default value is &t;. When <emphasis>set</emphasis> is &t; and
+ <emphasis>target-slot</emphasis> is undefined, the join slot will contain
+ a list of instances of the join class. Whereas, if <emphasis>target-slot</emphasis> is defined,
+ then the join slot will contain a list of pairs of <emphasis>(target-value join-instance)</emphasis>.
+ When <emphasis>set</emphasis> is &nil;, the join slot will contain a single instances.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:type</parameter> - for slots of
+ <parameter>:db-kind</parameter> <parameter>:base</parameter> or
+ <parameter>:key</parameter>, the <parameter>:type</parameter> slot
+ option has a special interpretation such that Lisp
+ types, such as string, integer and float are
+ automatically converted into appropriate SQL types for
+ the column onto which the slot maps. This behaviour may
+ be overridden using the <parameter>:db-type</parameter> slot
+ option. The valid values are:
+ <simplelist>
+ <member>
+ <parameter>string</parameter> - a variable length character field up to
+ <link linkend="default-string-length">*default-string-length*</link> characters.
+ </member>
+ <member>
+ <parameter>(string n)</parameter> - a fixed length character field
+ <parameter>n</parameter> characters long.
+ </member>
+ <member>
+ <parameter>varchar</parameter> - a variable length character field up to
+ <link linkend="default-string-length">*default-string-length*</link> characters.
+ </member>
+ <member>
+ <parameter>(varchar n)</parameter> - a variable length character field up to
+ <parameter>n</parameter> characters in length.
+ </member>
+ <member>
+ <parameter>char</parameter> - a single character field
+ </member>
+ <member><parameter>integer</parameter> - signed integer at least 32-bits wide</member>
+ <member><parameter>(integer n)</parameter></member>
+ <member><parameter>float</parameter></member>
+ <member><parameter>(float n)</parameter></member>
+ <member><parameter>long-float</parameter></member>
+ <member><parameter>number</parameter></member>
+ <member><parameter>(number n)</parameter></member>
+ <member><parameter>(number n p)</parameter></member>
+ <member>
+ <parameter>tinyint</parameter> - An integer column 8-bits
+ wide. [not supported by all database backends]
+ </member>
+ <member>
+ <parameter>smallint</parameter> - An integer column 16-bits
+ wide. [not supported by all database backends]
+ </member>
+ <member>
+ <parameter>bigint</parameter> - An integer column
+ 64-bits wide. [not supported by all database backends]
+ </member>
+ <member>
+ <parameter>universal-time</parameter> - an integer
+ field sufficiently wide to store a
+ universal-time. On most databases, a slot of this
+ type assigned a SQL type of
+ <parameter>BIGINT</parameter>
+ </member>
+ <member>
+ <parameter>wall-time</parameter> - a slot which
+ stores a date and time in a SQL timestamp
+ column. &clsql; provides a number of time
+ manipulation functions to support objects of type
+ <type>wall-time</type>.
+ </member>
+ <member>
+ <parameter>duration</parameter> - stores a <type>duration</type> structure.
+ &clsql; provides routines for <type>wall-time</type> and <type>duration</type>
+ processing.
+ </member>
+ <member><parameter>boolean</parameter> - stores a &t; or &nil; value.</member>
+ <member>
+ <parameter>generalized-boolean</parameter> - similar
+ to a <parameter>boolean</parameter> in that either a
+ &t; or &nil; value is stored in the SQL
+ database. However, any Lisp object can be stored in
+ the Lisp object. A Lisp value of &nil; is stored as
+ <constant>FALSE</constant> in the database, any
+ other Lisp value is stored as
+ <constant>TRUE</constant>.
+ </member>
+ <member>
+ <parameter>keyword</parameter> - stores a keyword
+ </member>
+ <member><parameter>symbol</parameter> - stores a symbol</member>
+ <member>
+ <parameter>list</parameter> - stores a list by writing it to a string. The items
+ in the list must be able to be readable written.
+ </member>
+ <member><parameter>vector</parameter> - stores a vector similarly to <parameter>list</parameter></member>
+ <member><parameter>array</parameter> - stores a array similarly to <parameter>list</parameter></member>
+ </simplelist>
+ </para>
+
+ </listitem>
+ <listitem>
+ <para>
+ <parameter>:column</parameter> - specifies the name of
+ the SQL column which the slot maps onto, if
+ <parameter>:db-kind</parameter> is not
+ <parameter>:virtual</parameter>, and defaults to the
+ slot name. If the slot name is used for the SQL column
+ name, any hypens in the slot name are converted
+ to underscore characters.
+ </para>
+ </listitem>
+ <listitem>