Generally speaking, it appears basic look-ups can be done without using JOIN, as long as the
column names are not ambiguous (the same in both tables).
http://platon.sk/projects/doc.php/phpMyEdit/html/configuration.input-restrictions.html

################################################################################

Post-initialized variables are sometimes easier to read:

	$opts['fdd']['facility_id'] = array(
	  'default'    => '',
	  'help|ACP'      => 'Select Facility',
	  'input'      => '',
	  'maxlen'     => 3,
	  'name'       => 'Facility',
	  'options'    => 'ACPVDFL',
	  'select'     => 'D',
	  'size|ACP'   => 4,
	  'sqlw'       => 'TRIM("$val_as")',
	  'sort'       => true
	);
	$opts['fdd']['col_name']['values']['db']     = 'mydb'; // optional
	$opts['fdd']['col_name']['values']['table']  = 'mytable';
	$opts['fdd']['col_name']['values']['column'] = 'id';
	$opts['fdd']['col_name']['values']['description']['columns'][0] = 'name_last';
	$opts['fdd']['col_name']['values']['description']['divs'][0]    = ', ';
	$opts['fdd']['col_name']['values']['description']['columns'][1] = 'name_first';
	// $opts['fdd']['col_name']['values']['filters'] = 'id IN (1,2,3)'; // optional WHERE clause
	$opts['fdd']['col_name']['values']['orderby'] = 'name_last,name_first'; // optional ORDER BY clause

An example which is comparable to that appearing above:

	$opts['fdd']['facility_id'] = array(
	  'default'    => '',
	  'help|ACP'      => 'Select Facility',
	  'input'      => '',
	  'maxlen'     => 3,
	  'name'       => 'Facility',
	  'options'    => 'ACPVDFL',
	  'select'     => 'D',
	  'size|ACP'   => 4,
	  'sqlw'       => 'TRIM("$val_as")',
	  'sort'       => true,
	  'values'     => array(
	    'table' => 'facilities',
	    'column' => 'id',
	    'description' => array(
	      'columns' => array('0' => 'name_last', '1' => 'name_first'),
         'divs' => array(', '),
	      'orderby' => array('0' => 'name_last,name_first')
	     )
	   )
	);

################################################################################

If the main column and the join look-up column share the same name, then references are ambiguos
to MySQL and JOIN syntax is required.

If you need to filter items in a second table in order to display them in a drop-down SELECT box,
then you need to use the join syntax.

You may find it easier to rename a column in the join table (and use the above lookup method)
than to implement the join syntax). However if your overall application is complex, it may
be impractical, or relatively impossible, to consider renaming a column.

Searching the forum at platon.sk for $join_table, $main_table, or related syntax may
lead you to additional examples of join syntax.
http://platon.sk/forum/projects/?c=5


-----

If using JOIN to achieve filtered drop-down selectors,
setting up variable names for the main table and column as
well as the join options makes the code a bit more portable
in terms of being able to copy it to other scripts and
implement the join again, with minimal effort (reducing coding errors).

/*
CREATE TABLE IF NOT EXISTS `domain` (
  `domain_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `domain` varchar(75) NOT NULL DEFAULT '',
  `parked_on` varchar(255) NOT NULL DEFAULT '',
  `host_name` varchar(50) NOT NULL DEFAULT '',
  `owner_id` smallint(5) unsigned NOT NULL DEFAULT '0',
  PRIMARY KEY (`domain_id`),
  KEY `domain` (`domain`),
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;

CREATE TABLE IF NOT EXISTS `contacts` (
  `contact_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `last_name` varchar(20) NOT NULL DEFAULT '',
  `first_name` varchar(20) NOT NULL DEFAULT '',
  `email1` varchar(50) NOT NULL DEFAULT '',
  `email2` varchar(50) NOT NULL DEFAULT '',
  PRIMARY KEY (`contact_id`),
  KEY `last_name` (`last_name`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;
*/

$main_table = 'domain';

$main_column = 'owner_id';

$join_table = 'contacts';

$join_column = 'contact_id';

$join_description_1 = 'last_name';

$join_description_2 = 'first_name';

$opts['fdd'][$main_column] = array(
  'default'    => '',
  'input'      => '',
  'name'       => 'Owner ID',
  'options'    => 'ACPVDFL',
  'required'   => true,
  'select'     => 'D',
  'size|ACP'   => 5,
  'sort'       => true,
  'sqlw'       => 'TRIM("$val_as")',
  'values'     => array(
    'join'        => '$main_table.$main_column = $join_table.$join_column', // single quotes, not ""
    'table'       => $join_table,
    'column'      => $join_column,
    'description' => array(
      'columns'   => array($join_description_1, $join_description_2), // last name, first name
      'divs'      => array(' ') // optional divider/separator
     ),
    'filters'     => $join_description_1.' <> "" AND '.$join_description_2.' <> ""', // Add/Change drop down restriction
    'orderby'     => $join_description_1.','.$join_description_2 // ORDER BY clause in Add/Change drop down
  )
);


-----

$join_table = 'mfg_authors'; // alias of the values table
$join_column = 'id'; // join column in the values table
$join_description = 'name'; // description column in the values table

$main_table = 'mfg_articles'; // alias of the main table
$main_column = 'author_id'; // join column in the main table

$opts['fdd']['author_id'] = array(
  'help|ACP'   => 'Limit 11 digits',
  'input'      => '',
  'maxlen'     => 11,
  'name'       => 'Author ID',
  'options'    => 'ACPVDFL',
  'required'   => true,
  'select'     => 'T',
  'size|ACP'   => 11,
  'sqlw'       => 'TRIM("$val_as")',
  'sort'       => true,
  'values' => array(
    'table'       => $join_table,
    'column'      => $join_column,
    'description' => $join_description,
    'join'        => '$main_table.$main_column = $join_table.$join_column'
  )
);
// Column type: int - int(11)

-----

Sometimes you want to restrict table joining on the output.

This is important in case where ['values']['column'] is not unique in ['values']['table'].

For this purpose, you can use:

   $opts['fdd']['col_name']['values']['join'] option.

These variables are available in this option:

   $main_table = ''; // alias of the main table

   $main_column = ''; // join column in the main table

   $join_table = ''; // alias of the values table

   $join_column = ''; // join column in the values table

   $join_description = ''; // description column in the values table

phpMyEdit will create by default

   $main_table.$main_column = $join_table.$join_column

join, what is sufficient the most cases. However you may
extend it with additional conditions as well.

Example 4-17. Table lookup with advanced joining

$opts['fdd']['col_name']['values']['join']
   = '$main_table.$main_column = $join_table.$join_column AND '
   . '$main_table.another_col = $join_table.another_col';

Please note that 'filters' is used for filtering items in dropdown
during ADD/EDIT mode (with a sql WHERE) while 'join' is useful for
having a correct LEFT JOIN against the main table in LIST/VIEW mode

$opts['fdd']['vendor']['values']['join'] =
   'PMEjoin0.part_no = PMEjoin1.part_no AND is_preferred = "true" ';

-----

un-tested:

//  1. Have an hidden virtual field that is doing the custom join :

$opts['fdd']['dummy_field'] = array(
  'input' => 'VR',
  'options' => '',
  'values' => Array(
    'table' => 'table_b',
    'column'      => 'id',
    'description' => 'id', //Required by the implementation
    'join'        => '$main_table.id = $join_table.id'
  )
);

// 2. then, use 'sql' field option to display correct value

$opts['fdd']['address'] = array(
  'name'    => 'Address',
  'options' => 'LVF',
  'sql'     => 'if(table_b.address is null, table_a.address, table_b.address)'
);

// But this will work only in LVF mode.


-------

May 2004 CVS version supports a new ['join'] option.

Here is my test details in case anyone else has the same question.

orders table
orderid
itemid

items table
itemid
name

CREATE TABLE `orders` (
`orderid` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
`itemid` INT UNSIGNED NOT NULL ,
PRIMARY KEY ( `orderid` )
);

CREATE TABLE `items` (
`itemid` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
`name` VARCHAR( 10 ) NOT NULL ,
PRIMARY KEY ( `itemid` )
);

INSERT INTO `items` ( `itemid` , `name` )
VALUES (
'1', 'test'
);

$opts['fdd']['orderid'] = array(
'name' => 'Orderid',
'select' => 'T',
'options' => 'AVCPDR', // auto increment
'maxlen' => 10,
'default' => '0',
'sort' => true
);

$opts['fdd']['itemid'] = array(
'name' => 'Part Number',
'select' => 'T',
'maxlen' => 11,
'default' => '0',
'required' => true,
'values' => array( 'table' => 'items', 'column' => 'itemid', 'description' => 'name' ),
'sort' => true
);


$opts['fdd']['vendor']['values']['join'] =
   'PMEjoin6.part_no = PMEtable0.part_no AND is_preferred = "TRUE" ';


Please note that 'filters' is used for filtering items in dropdown during ADD/EDIT mode (with a SQL WHERE) while 'join' is useful for having a correct LEFT JOIN against the main table in LIST/VIEW mode.

$opts['fdd']['vendor']['values']['join'] =
   'PMEjoin0.part_no = PMEjoin1.part_no
   AND
   is_preferred = "true" ';

Maybe will do the correct join you want.

-----

excerpt from related, older project

<?php

// my_mdd_tel_did.php created Thu, 17 Jul 2003 16:12:28 -0600

// Certain WHERE statements require prepending PMEtable0
// or PMEjoinX where X is a number before table name.

$opts['tb'] = 'mdd_tel_did'; // Table name

// ob_start('ob_gzhandler'); // Send compressed data

require('pme-vars.php'); // Logon ($hn, $db, $un, $pw)

array_key_exists('grouping',$_GET) ? $grouping = $_GET['grouping'] : $grouping = 0;

$opts['cgi']['persist'] = array('grouping' => $grouping);

if($grouping == 0){
   $opts['filters'] = 'PMEjoin1.FullName NOT LIKE "%..%"';
   $opts['sort_field'] = array('AgentID');
   $oper_label = empty($operation) ? 'Telephone DID Configuration' : $operation;
}elseif($grouping == 1){
   $opts['sort_field'] = array('System', 'AgentID');
   $oper_label = empty($operation) ? 'Click column titles to sort records' : $operation;
}

switch($HTTP_SERVER_VARS['DOCUMENT_ROOT'])
{
   // Set error_reporting.
   Case 'C:/apache/htdocs':
      error_reporting(E_ALL & ~E_NOTICE);
      break;
   default:
      error_reporting(0);
      break;
};

?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-style-type" content="text/css">
<meta name="googlebot" content="index, nofollow, noarchive">
<meta name="robots" content="index, nofollow, noarchive, nocache, noimageindex, nomediaindex">

<?php
// If old Netscape browser, require 'safe' stylesheet.
if(stristr($HTTP_USER_AGENT,'Mozilla/4.5') || stristr($HTTP_USER_AGENT,'Mozilla/4.7') || stristr($HTTP_USER_AGENT,'Mozilla/4.8')){
   require('style.ngeneric.php');
}else{
   // $cfg['bdr_bottom'] = 4; // [1|4] (see style.php)
   require('style.php');
}
?>

<title>my_mdd_tel_did.php</title>

</head>

<body>

<!-- Container table for $operation labels, phpMyEdit form, and text below the form. -->
<p style="color:aqua">Reminder: AgentID used to lookup names is actually looking up the ID field in mdd_staff (not AgentID)</p>

<table class="container" cellspacing="0" cellpadding="5">

<?php

// First table row/cell appears above phpMyEdit form row/cell.


// echo "\n".'<tr><td><h3 style="color:#99ccff">'.$grouping.'</h3></td></tr>'."\n\n";
echo "\n".'<tr><td><h3 style="color:#99ccff">'.$oper_label.'</h3></td></tr>'."\n\n";

?>

<!-- Begin the "container table" cell for the phpMyEdit form. -->

<tr><td>

<?php

// phpMyEdit variables: http://platon.sk/projects/doc.php/phpMyEdit/html/index.html

$opts['key'] = 'RecordID'; // Primary key checked

$opts['key_type'] = 'int'; // Primary key column type

$opts['inc'] = -1; // Number of rows to include in List mode.

// General permission options:
$opts['options'] = 'ACPVDFL'; // [A|C|P|V|D|F|I|L] (L is always assumed and can be omitted.)

$opts['multiple'] = '4'; // SELECT box size (if SET/ENUM column types exist).

// Navigation: Text/Button/Graphic with Up/Down - [T|B|G] + [U|D]
$opts['navigation'] = 'TUD';

$opts['display'] = array(  // Display: query, sort order, timer [true|false].
   'query' => true,
   'sort'  => true,
   'time'  => false
);

$opts['language'] = $HTTP_SERVER_VARS['HTTP_ACCEPT_LANGUAGE'];

// Note: permission options for specific columns may be changed in the field arrays below.


// RecordID - smallint(3) - int
$opts['fdd']['RecordID'] = array(
  'name'     => 'RecordID',
  'select'   => 'T',
  'options'  => 'VDR',
  'maxlen'   => 3,
  'default'  => '0',
  'required' => true,
  'sort'     => true
);
$opts['fdd']['RecordID']['help|ACP'] = 'AUTO-INCREMENT';
// $opts['fdd']['RecordID']['options'] = 'ACPVDLF';


// AgentID - smallint(5) - int
$opts['fdd']['AgentID'] = array(
  'name'     => 'Agent ID',
  'select'   => 'D',
  'maxlen'   => 5,
  'default'  => '0',
  'required' => true,
  'sort'     => true
);
$opts['fdd']['AgentID']['help|ACP'] = 'Lookup';
// $opts['fdd']['AgentID']['options'] = 'ACPVDLF';
$opts['fdd']['AgentID']['values']['table'] = 'mdd_staff'; // other table
$opts['fdd']['AgentID']['values']['column'] = 'ID'; // column e.g. id
$opts['fdd']['AgentID']['values']['description']['columns']['0'] = 'FullName';
$opts['fdd']['AgentID']['nowrap'] = 'true';

// Number - varchar(15) - string
$opts['fdd']['Number'] = array(
  'name'     => 'A/C/Phone',
  'select'   => 'D',
  'maxlen'   => 15,
  'required' => false,
  'sort'     => true
);
$opts['fdd']['Number']['help|ACP'] = 'XXX-XXX-XXXX';
// $opts['fdd']['Number']['options'] = 'ACPVDLF';
$opts['fdd']['Number']['nowrap'] = 'true';


// Extension - smallint(4) - int
$opts['fdd']['Extension'] = array(
  'name'     => 'Ext.',
  'select'   => 'D',
  'maxlen'   => 4,
  'default'  => '0',
  'required' => false,
  'sort'     => true
);
$opts['fdd']['Extension']['help|ACP'] = 'XXX';
// $opts['fdd']['Extension']['options'] = 'ACPVDLF';
// $opts['fdd']['Extension']['css'] = array('postfix' => 'right-justify');


/*
**************** Abandoned after creating the above lookup field *********
      // FullName - varchar(40) - string
      $opts['fdd']['FullName'] = array(
        'name'     => 'FullName',
        'select'   => 'T',
        'maxlen'   => 40,
        'required' => false,
        'sort'     => true
      );
*/


// System - varchar(40) - string
$opts['fdd']['System'] = array(
  'name'     => 'Location',
  'select'   => 'D',
  'maxlen'   => 40,
  'required' => false,
  'sort'     => true
);
$opts['fdd']['System']['help|ACP'] = 'System components (omit for people)';
// $opts['fdd']['System']['options'] = 'ACPVDLF';


// DID - smallint(3) - int
$opts['fdd']['DID'] = array(
  'name'     => 'DID',
  'select'   => 'D',
  'maxlen'   => 3,
  'default'  => '0',
  'required' => false,
  'sort'     => true
);
$opts['fdd']['DID']['help|ACP'] = 'Limit 3 characters.';
// $opts['fdd']['DID']['options'] = 'ACPVDLF';
$opts['fdd']['DID']['css'] = array('postfix' => 'right-justify');


// Phone - varchar(35) - string
$opts['fdd']['Phone'] = array(
  'name'     => 'Hardware',
  'select'   => 'D',
  'maxlen'   => 35,
  'required' => false,
  'sort'     => true
);
$opts['fdd']['Phone']['help|ACP'] = 'Select';
// $opts['fdd']['Phone']['options'] = 'ACPVDLF';
// $opts['fdd']['Phone']['nowrap'] = 'true';
$opts['fdd']['Phone']['values2'] = array(
  '' => '',
  '7* TO ENTER MESSAGING' => '7* TO ENTER MESSAGING',
  'FAX' => 'FAX',
  'MLX16DP' => 'MLX16DP',
  'MLX20L' => 'MLX20L',
  'Virtual' => 'Virtual'
);


// EmailCk - tinyint(1) - int
$opts['fdd']['EmailCk'] = array(
  'name'     => 'EmailCk',
  'select'   => 'D',
  'maxlen'   => 1,
  'default'  => '0',
  'required' => false,
  'sort'     => true
);
$opts['fdd']['EmailCk']['help|ACP'] = 'Select';
// $opts['fdd']['EmailCk']['options'] = 'ACPVDLF';
$opts['fdd']['EmailCk']['values2'] = array(
  '0' => 'No',
  '1' => 'Yes'
);


// Field list: RecordID, AgentID, FullName, System, DID, Number, Extension, Phone, EmailCk

// Variables list: $RecordID, $AgentID, $FullName, $System, $DID, $Number, $Extension, $Phone, $EmailCk

require_once('phpMyEdit.tabclass.php'); // Work-horse.

new phpMyEdit($opts); // Form is generated here.

?>


</td></tr> <!-- Close container table cell (end phpMyEdit form above) -->

<tr><td>

<p style="color:#00ffff">
Filters:
<?php
echo $grouping == 0 ? '<a href="my_mdd_tel_did.php?grouping=1" title="All Information" style="color:#00ffff">All Information</a>' : '';
echo $grouping == 1 ? '<a href="my_mdd_tel_did.php?grouping=0" title="People Only" style="color:#00ffff">People Only</a>' : '';
?>
</p>

</td></tr>

<tr><td><br>
<p style="color:#99ccff">[V]iew - [C]hange - co[P]y - [D]elete</p>
<p style="color:#99ccff"><?php echo $opts['tb'].' - '.basename($_SERVER["PHP_SELF"]); ?></p>
</td></tr>

</table>
</body>
</html>



---------

http://platon.sk/forum/projects/viewtopic.php?t=455

If you want to show or edit values from two both tables.

TableA

   A_ID
   A_FD1
   A_FD2
   B_ID
   A_FD3

TableB

   B_ID
   B_FD1
   B_FD2
   B_FD3

TableA is connected to TableB via B_ID


$opts['fdd']['A_FD1'] = array(
'name' => 'TableA_FD1',
'select' => 'T',
'maxlen' => 20,
'sort' => true
);

$opts['fdd']['A_FD2'] = array(
'name' => 'TableA_FD2',
'select' => 'T',
'maxlen' => 20,
'sort' => true
);

$opts['fdd']['B_ID'] = array(
'name' => 'TableA_B_ID', // TableA.B_ID ref
'select' => 'T',
'maxlen' => 20,
'sort' => true
);

$opts['fdd']['B_ID']['values']['table'] = 'TableB';
$opts['fdd']['TechTypeID']['values']['column'] = 'B_ID';
$opts['fdd']['TechTypeID']['values']['description'] = 'B_FD1';

$opts['fdd']['B_ID'] = array(
'name' => 'TableA_B_ID', // TableA.B_ID ref
'select' => 'D',
'maxlen' => 20,
'sort' => true
);

$opts['fdd']['B_ID']['values']['table'] = 'TableB';
$opts['fdd']['TechTypeID']['values']['column'] = 'B_ID';
$opts['fdd']['TechTypeID']['values']['description'] = 'B_FD2';


AND SO ON... you can call as many fields from tableB as you want ...
either in Text Boxes or DropDown. If you have a Ref for TableC
in TableA like C_ID you could also call other values from TableC
if you like, i just don't know if there is a join limit for
conecting tables this way.