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=head1 Synopsis

	use DBIx::HTML::ClientDB;

	my($object) = DBIx::HTML::ClientDB -> new
	(
		dbh          => $dbh,
		row_headings => 'Unit code,Unit code,Campus name,Unit name',
		sql          => 'select unit_code, unit_code, campus_name, unit_name ' .
		                'from unit, campus where unit_campus_id = campus_id ' .
		                'order by unit_code',
	);

	print $object -> javascript_for_client_db();
	print $object -> table();
	print $object -> javascript_for_client_init();

=head1 Description

This module takes a db handle, an SQL statement and a specially-formatted
row_headings parameter, and builds an array of rows as returned by the SQL.

Then you ask for that array in HTML, ie as a table.

After a call to the table() method, you can call the size() method if
you need to check how many rows were returned by the SQL you used.

Neither the module CGI.pm, nor any of that kidney, are used by this module.
We simply output pure HTML.

However, for simplicity, this document pretends you are using CGI.pm rather
than an alternative. The sentences would become too convoluted otherwise.

The output table is formatted as N rows of 2 columns:

=over 4

=item First column

The first column contains the row headings you supply in the 'row_headings' parameter.
'row_headings' is a comma-separated list of strings you want to appear in the first
column of the table.

There must be one string in 'row_headings' for each column mentioned in the SQL.

=item Second column

The second column contains the 'current record' in the database.

=back

Now for the rows:

=over 4

=item First row

The first row contains the first prompt string in the first column.

The first row contains a HTML popup menu in the second column.

This menu is what you use to choose the 'current record' in the database.

Since two (2) SQL columns are used to build this menu, two (2) strings from
the row_headings parameter are consumed building the first row. The first of
these 2 strings appears in the first column, as explained above. The second
of these 2 strings is, much to your amazement, discarded!

This way of doing things makes it easy for you to count row_heading strings and
their corresponding SQL columns, and makes it easy for me to cross-check your
ability to count to 2 :-).

=item Other rows

Each other row contains a field in the 'current record'. The value in the first
column comes from the row_headings parameter, and the value in the second column
comes from the database.

=back

The sum result is menu-driven access to the data returned by the SQL. All this
is downloaded from your CGI script to the web client. Since changing the current
menu item updates the other fields in this table using JavaScript, no message is
sent to the web server, and hence you have maximum speed of access.

The whole point of the exercise is to give you simple code for simple access to
simple data.

See examples/test-clientdb.cgi for an example which will make all this clear.

=head1 Distributions

This module is available both as a Unix-style distro (*.tgz) and an
ActiveState-style distro (*.ppd). The latter is shipped in a *.zip file.

See http://savage.net.au/Perl-modules/html/installing-a-module.html for
help on unpacking and installing each type of distro.

=head1 Usage

You create an object of the class by calling the constructor, 'new'.

Now call various methods to get the HTML and JavaScript.

Lastly, display the HTML as part of a form. You don't need a submit button
because there is no need to transmit your menu selection to the CGI script.
It's all about convenient access to a small database. Of course, you can
easily use this as the basis of a more complex record-selection system.

Instead of the method javascript_for_client_init(), you can call the method
javascript_for_client_on_load() to initialize a JavaScript onLoad event handler.

Note: The HTML menu name and all JavaScript function and global variable names
have been deliberately chosen so as to not clash with other modules of mine in the
DBIx::HTML::* namespace. Hence these modules can, in theory, all be used to build a
single web page, and indeed, can (I hope) all be used to build a single form. No,
I didn't actually test it.

=head1 Options

Here, in alphabetical order, are the options accepted by the constructor,
together with their default values.

=over 4

=item border => 0

This specifies whether or not the HTML table returned by the table() method
has the border option set.

Valid values are 0 and 1.

This option is not mandatory.

=item dbh => ''

Pass in an open database handle.

This option is mandatory.

=item default => ''

Pass in the string (from SQL column 2) which is to be the default item on the
popup menu. You supply here the visible menu item, not the value associated with
that menu item.

If default is not given a value, the first menu item becomes the default.

See the discussion of the sql option for details about the menu items.

This option is not mandatory.

=item form_name => 'dbix_client_form'

The value of this parameter becomes the name of the form used in the
JavaScript, and must be the name used by you in your call to CGI's start_form()
or start_multipart_form() method.

This option is not mandatory, since it has a default value.

=item max_width => 0

When the database field values displayed in the second column of the table are
input fields, this value becomes the 'size' parameter of those input fields.

A value of 0 means the data will be scanned and a value chosen which ensures
no data is truncated in order to display the database field values.

This option is not mandatory.

=item menu_name => 'dbix_client_menu'

The value of this parameter is what you would pass into a CGI object when you
call its param() method to retrieve the user's selection.

Hence you would do something like:

	my($name)   = 'fancy_menu';
	my($object) = DBIx::HTML::ClientDB -> new(menu_name => $name, ...);
	my($q)      = CGI -> new();
	my($id)     = $q -> param($name) || '';

This option is not mandatory, since it has a default value.

=item row_headings => 'a,b,...'

Pass in a comma-separated list of strings to use in the first column of the table.

There must be one string in 'row_headings' for each column mentioned in the SQL.

Since two (2) SQL columns are used to build the menu, two (2) strings from
the row_headings parameter are consumed building the first row. The first of
these 2 strings appears in the first column, as explained above. The second
of these 2 strings is, much to your amazement, discarded!

This way of doing things makes it easy for you to count row_heading strings and
their corresponding SQL columns, and makes it easy for me to cross-check your
ability to count to 2 :-).

This option is mandatory.

=item sql => ''

Pass in the SQL used to select the data.