Location: PHPKode > projects > Open Media Collectors Database > functions/item.php
<?php
/* 	
	Open Media Collectors Database
	Copyright (C) 2001,2006 by Jason Pell

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

include_once("./functions/database.php");
include_once("./functions/logging.php");
include_once("./functions/item_attribute.php");
include_once("./functions/item_type.php");
include_once("./functions/theme.php");
include_once("./functions/utils.php");
include_once("./functions/datetime.php");
include_once("./functions/status_type.php");
include_once("./functions/BooleanParser.class.inc");
include_once("./functions/widgets.php");
include_once("./functions/parseutils.php");
include_once("./functions/item_type_group.php");

/**
	Will check that the $uid has an item_instance for item_id.  If instance_no specified,
	will check that the user owns the specified instance, otherwise this function is
	only checking that the $uid owns at least one instance of the item.
*/	
function is_user_owner_of_item($item_id, $instance_no, $user_id = NULL)
{
	if(strlen($user_id)==0)
		$user_id = get_opendb_session_var('user_id');
		
	$query = "SELECT 'x' FROM item_instance WHERE item_id = '$item_id' AND owner_id = '$user_id' ";
	if(is_numeric($instance_no))
		$query .= " AND instance_no = '$instance_no' ";

	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		// The very fact that at least one row was returned indicates that owner
		// has at least one instance of item.
		return TRUE;
	}

	//else
	return FALSE;
}

/**
*/
function fetch_item_owner_id($item_id, $instance_no)
{
	$query = "SELECT owner_id FROM item_instance WHERE item_id = '$item_id' AND instance_no = '$instance_no'";
	$result = db_query($query);
	if ($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		if ($found)
		{
			db_free_result($result);
			return $found['owner_id'];
		}
	}
	//else
	return FALSE;
}

function fetch_item_s_status_type($item_id, $instance_no)
{
	$query = "SELECT s_status_type FROM item_instance WHERE item_id = '$item_id' AND instance_no = '$instance_no'";
	$result = db_query($query);
	if ($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		if ($found)
		{
			db_free_result($result);
			return $found['s_status_type'];
		}
	}
	//else
	return FALSE;	
}

/**
	Returns a count of item instances stored in the database, or false if none found.
	NOTE: If $s_item_type is specified, only the given $s_item_type is counted (otherwise all)
*/
function fetch_item_instance_cnt($s_item_type = NULL)
{
	$query = "SELECT count(ii.item_id) as count ";
	$from = "FROM item_instance ii, s_status_type sst, user u, item i ";
	$where = "WHERE i.id = ii.item_id AND u.user_id = ii.owner_id AND u.active_ind = 'Y' AND sst.s_status_type = ii.s_status_type ";
			
	if($s_item_type)
	{
		$where .= " AND i.s_item_type = '".$s_item_type."' ";
	}
	
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$where .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$query .= "$from $where";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if ($found!== FALSE)
			return $found['count'];
	}

	//else
	return FALSE;
}

/**
	Returns resultset of item_instance's for the particular item_id
*/
function fetch_item_instance_rs($item_id, $owner_id = NULL)
{
	// so that both resultset use item_id for the item.id or item_instance.item_id!!!
	$query = "SELECT ii.item_id, ii.instance_no, ii.owner_id, ii.borrow_duration, ii.s_status_type, ii.status_comment ".
			" FROM item_instance ii, s_status_type sst, user u, item i".
			" WHERE i.id = ii.item_id AND 
					u.user_id = ii.owner_id AND 
					u.active_ind = 'Y' AND 
					sst.s_status_type = ii.s_status_type AND 
					ii.item_id='".$item_id."' ".(strlen($owner_id)>0?"AND ii.owner_id = '$owner_id'":"");
	
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$query .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$query .= " ORDER BY ii.instance_no	";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
		return $result;
	else	
		return FALSE;
}

/**
	Returns a count of items owned by the specified owner_id, or FALSE if no records.
	Assumes this will NOT be called for INACTIVE users, if being called from Statistics
	
	NOTE: If $s_item_type is specified, only the given s_item_type is counted (otherwise all)
	
*/
function fetch_owner_item_cnt($owner_id, $s_item_type = NULL)
{
	$query = "SELECT count(ii.item_id) AS count ";
	$from = "FROM item_instance ii, s_status_type sst, item i ";
	$where = "WHERE i.id = ii.item_id AND sst.s_status_type = ii.s_status_type ";
			
	if($s_item_type)
	{
		$where .= "AND i.s_item_type='".$s_item_type."' ";
	}
	$where .= "AND ii.owner_id = '$owner_id' "; 
	
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$where .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$query .= "$from $where";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if ($found!== FALSE)
			return $found['count'];
	}

	//else
	return FALSE;
}

/*
* 	We do not know which s_status_type's the get_opendb_session_var('user_type')
* 	can have access to so we include a join to s_status_type to hide any
* 	items with a s_status_type the current user should not see.
*/
function fetch_owner_s_status_type_item_cnt($owner_id, $s_status_type)
{
	$query = "SELECT count(ii.item_id) as count ".
			"FROM item_instance ii, s_status_type sst, item i ".
			"WHERE i.id = ii.item_id AND sst.s_status_type = ii.s_status_type AND ii.owner_id='".$owner_id."' AND ii.s_status_type = '$s_status_type' ";

	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$query .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if ($found !== FALSE)
			return $found['count'];
	}

	//else
	return FALSE;
}

/**
	Returns a count of items in the specified $s_item_type category, or FALSE if no records.
	NOTE: If $s_item_type is specified, only the given s_item_type is counted (otherwise all)
*/
function fetch_category_item_cnt($category, $s_item_type = NULL)
{
	$query = "SELECT COUNT(DISTINCT ii.item_id) AS count ".
			"FROM item i, item_instance ii, s_status_type sst, user u, s_attribute_type sat, s_item_attribute_type siat, item_attribute ia ".
			"WHERE u.user_id = ii.owner_id AND ".
			"siat.s_item_type = i.s_item_type AND ".
			"sat.s_attribute_type = siat.s_attribute_type AND ".
			"sat.s_field_type = 'CATEGORY' AND ".
			"ia.s_attribute_type = siat.s_attribute_type AND ".
			"ia.item_id = ii.item_id AND ".
			"(ia.instance_no = 0 OR ia.instance_no = ii.instance_no) AND ".
			"ia.order_no = siat.order_no AND ".
			"u.active_ind = 'Y' AND ".
			"sst.s_status_type = ii.s_status_type AND ".
			"i.id = ii.item_id AND ".
			"ia.lookup_attribute_val = '".$category."'";
	
	if($s_item_type)
	{
		$query .= " AND i.s_item_type='".$s_item_type."' ";
	}
	
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$query .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if ($found!== FALSE)
		{
			return $found['count'];
		}
	}

	//else
	return FALSE;
}

/*
* Returns a list of items owned by the specified owner.
* item_id,instance_no,title
* 
* Note: Used exclusively in User Admin.  This we can restrict
* set returned, to only those records which are accessible to
* the administrator.
*/
function fetch_owner_item_instance_rs($owner_id)
{
	$query = "SELECT ii.item_id, ii.instance_no, ii.s_status_type, ii.status_comment, ii.borrow_duration, ii.owner_id, i.title, i.s_item_type 
			FROM item i, item_instance ii 
			WHERE i.id = ii.item_id AND ii.owner_id='".$owner_id."' ";
	 
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
		return $result;
	else
		return FALSE;
}

define('RELATED_CHILDREN_MODE', 'CHILDREN');
define('RELATED_PARENTS_MODE', 'PARENTS');

function fetch_item_instance_relationship_rs($item_id, $instance_no = NULL, $related_mode = RELATED_CHILDREN_MODE)
{
	$query = "SELECT DISTINCT ii.item_id, 
					ii.instance_no, 
					i.title,
					i.s_item_type,
					ii.s_status_type,
					ii.owner_id,
					ii.status_comment
			FROM	item_instance_relationship iir,
					item_instance ii,
				 	item i,
				 	s_status_type sst
			WHERE 	sst.s_status_type = ii.s_status_type AND 
					ii.item_id = i.id AND ";
			
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$query .= " ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') AND ";
	}
	
	if($related_mode == RELATED_CHILDREN_MODE)
	{
		$query .= "ii.item_id = iir.related_item_id AND
					ii.instance_no = iir.related_instance_no ";
		
		$query .= "AND iir.item_id = $item_id ";
		if(is_numeric($instance_no))
		{
			 $query .= "AND iir.instance_no = $instance_no";
		}
	}
	else 
	{
		$query .= "ii.item_id = iir.item_id AND
					ii.instance_no = iir.instance_no ";
		
		$query .= "AND iir.related_item_id = $item_id ";
		if(is_numeric($instance_no))
		{
			 $query .= "AND iir.related_instance_no = $instance_no";
		}
	}

	$query .= " ORDER BY 1, 2 ASC";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
		return $result;
	else
		return FALSE;
}

/**
 * Does current item have any related items
 *
 * @param unknown_type $item_id
 * @param unknown_type $instance_no
 * @return unknown
 */
function is_exists_item_instance_relationship($item_id, $instance_no)
{
	$query = "SELECT 'X'
			FROM item_instance_relationship
			WHERE item_id = $item_id AND
				instance_no = $instance_no";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}

/**
 * Check whether item instance is referenced in at least one item instance relationship.  Where parent_item_id and
 * parent_instance_no are specified, relationship checking will not count a relationship featuring this parent - good
 * for when deleting item and we have a parent context.
 *
 * @param unknown_type $item_id
 * @param unknown_type $instance_no
 */
function is_exists_related_item_instance_relationship($item_id, $instance_no, $parent_item_id = NULL, $parent_instance_no = NULL)
{
	$query = "SELECT 'X'
			FROM item_instance_relationship
			WHERE related_item_id = $item_id AND
				related_instance_no = $instance_no";

	if(is_numeric($parent_item_id) && is_numeric($parent_instance_no))
	{
		$query .= " AND item_id <> $parent_item_id AND instance_no <> $parent_instance_no ";
	}
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}

//
// Returns an associative array for a single item.
//id,owner_id,title,s_item_type
//
function fetch_item_instance_r($item_id, $instance_no)
{
	$query = "SELECT ii.item_id, ii.instance_no, ii.s_status_type, ii.status_comment, ii.borrow_duration, ii.owner_id, i.title, i.s_item_type 
			FROM item i, item_instance ii 
			WHERE i.id = ii.item_id AND i.id ='".$item_id."' AND ii.instance_no = '".$instance_no."'";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		return $found;
	}
	else
		return FALSE;
}

function fetch_item_r($item_id)
{
	$query = "SELECT id as item_id, title, s_item_type FROM item WHERE id = '".$item_id."'";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		return $found;
	}
	else
		return FALSE;
}

//
// Returns an associative array for a single item.
//id,owner_id,title,s_item_type
//
function fetch_child_item_r($item_id)
{
	return fetch_item_r($item_id);
}

/**
	Return the item title.
*/
function fetch_item_title($item_id)
{
	// Only load previous record if edit.
	$query = "SELECT title FROM item WHERE id = '".$item_id."'"; 
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		return $found['title'];
	}
	else
		return FALSE;
}

//
// Return the item title.
//
function fetch_item_type($item_id)
{
	// Only load previous record if edit.
	$query = "SELECT s_item_type FROM item WHERE id = '".$item_id."'"; 
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		return $found['s_item_type'];
	}
	else
		return FALSE;
}

/**
	Will ascertain whether an item already exists with the same information:
		title, s_item_type
	OR
		title, s_item_type, owner_id		
*/
function is_exists_title($title, $s_item_type, $owner_id=NULL)
{
	$query = "SELECT 'x' FROM item i,item_instance ii, s_status_type sst, user u ".
   			"WHERE i.id = ii.item_id AND ".
			"u.user_id = ii.owner_id AND ".
			"u.active_ind = 'Y' AND ".
			"sst.s_status_type = ii.s_status_type AND ".
			"i.title = '".addslashes($title)."' AND ".
           	"i.s_item_type = '".$s_item_type."' ";
			
	if(strlen($owner_id)>0)
		$query .= " AND ii.owner_id = '".$owner_id."'";

	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$query .= " AND ( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}

/**
	Assumes that lock_item_instance has been called to ensure that
	between delete of item_instance and delete of item, no further activity
	can occur on the table.
	
	If '$instance_no' specified, will test whether the specific instance 
	exists or not; Other wise will test whether any instances exist.

	This will not cater for 'linked' items which do not have a 
	item_instance record.
*/
function is_exists_item_instance($item_id, $instance_no=NULL)
{
	$query = "SELECT 'x' FROM item_instance WHERE item_id = '$item_id' ";
	if($instance_no)
		$query .= "AND instance_no = '$instance_no'";
	$query .= " LIMIT 0,1";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}

	//else
	return FALSE;
}

function is_exists_item_instance_with_owner($owner_id)
{
	$query = "SELECT 'x' FROM item_instance WHERE owner_id = '$owner_id'";
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}

	//else
	return FALSE;
}

function is_exists_item_instance_with_owner_and_status($item_id, $s_status_type, $owner_id)
{
	$query = "SELECT 'x' FROM item_instance WHERE item_id = '$item_id' AND owner_id = '$owner_id' AND s_status_type = '$s_status_type'";

	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}

	//else
	return FALSE;
}

/**
	Checks if the underlying item record actually exists or not.
*/
function is_exists_item($item_id)
{
	$query = "SELECT 'x' FROM item WHERE id = '$item_id'";

	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		db_free_result($result);
		return TRUE;
	}

	//else
	return FALSE;
}

/**
	Assumes that lock_item_instance has been called to 
	ensure that the max_instance_no DOES NOT CHANGE between the select
	and insert.
*/
function fetch_max_instance_no($item_id)
{
	$query = "SELECT MAX(instance_no) as instance_no FROM item_instance WHERE item_id = $item_id";
	
	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if ($found!== FALSE)
			return $found['instance_no'];
	}

	//else
	return FALSE;
}

/**
	@param item_where_clause - the result of running the item_where_clause statement.
	
	@param $column_display_config_rs - Format of this array is:
	 	array(
	 		s_attribute_type => '',
			order_no=>'',
	 		value => '',
	 		lookup => '',
	 		attr_match => '',
			search_attribute_ind => 'Y');
	 
	 Arrays where value is defined, attr_match is one of 'word' or 'partial'
	 and search_attribute_ind = 'y' will be included in the select statement.
*/
function fetch_item_listing_cnt($HTTP_VARS, $column_display_config_rs=NULL)
{
	$query = "SELECT COUNT(DISTINCT i.id, ii.instance_no";
	if(is_array($column_display_config_rs))
	{
		for($i=0; $i<count($column_display_config_rs); $i++)
		{
			// ignore all other configuration columns as they are already included
			if($column_display_config_rs[$i]['column_type'] == 's_attribute_type')
			{
				// if not an order by column, we want to generate the fields individually in the listings page.
				if($column_display_config_rs[$i]['orderby_support_ind'] === 'Y')
				{
					if(strlen($column_display_config_rs[$i]['attribute_val'])>0 && 
							($column_display_config_rs[$i]['attr_match'] == 'word' || $column_display_config_rs[$i]['attr_match'] == 'partial') &&
							$column_display_config_rs[$i]['search_attribute_ind']  == 'y')
					{
						$query .= ', ifnull(ia'.$i.'.attribute_val,ia'.$i.'.lookup_attribute_val)';
					}
				}
			}
		}
	}
	$query .= ") AS count ";
	
	$query .= from_and_where_clause($HTTP_VARS, $column_display_config_rs, 'COUNT');

	//echo "\n<code>Listing Query: $query</code>";

	$result = db_query($query);
	if($result && db_num_rows($result)>0)
	{
		$found = db_fetch_assoc($result);
		db_free_result($result);
		if($found!==FALSE)
			return $found['count'];
	}
	
	//else
	return FALSE;
}

/**
	Add the SELECT and ORDER BY CLAUSES

	@param $HTTP_VARS
	@param $column_display_config_rs

	@param	$order_by by should be one of "s_item_type, owner_id, title, update_on"
		The $order_by value will control which order column is first in the list, the rest
		will be filled in after with defaults.
	
	@param	$sortorder will be either "asc" or "desc"  if not defined it will default to "asc"
	@param	$index is the LIMIT value to apply.
*/
function fetch_item_listing_rs($HTTP_VARS, &$column_display_config_rs, $order_by, $sortorder, $start_index=NULL, $items_per_page=NULL)
{
	$query .= 'SELECT DISTINCT i.id AS item_id, ii.instance_no, ii.s_status_type, ii.status_comment, ii.owner_id, ii.borrow_duration, i.s_item_type, i.title, UNIX_TIMESTAMP(ii.update_on) AS update_on';

	$attr_order_by = NULL;
	$column_order_by = NULL;
	if(is_array($column_display_config_rs))
	{
		for($i=0; $i<count($column_display_config_rs); $i++)
		{
			if($column_display_config_rs[$i]['column_type'] == 's_attribute_type')
			{
				// if not an order by column, we want to generate the fields individually in the listings page.
				if($column_display_config_rs[$i]['orderby_support_ind'] === 'Y' || $column_display_config_rs[$i]['search_attribute_ind'] === 'y')
				{
					$fieldname = get_field_name($column_display_config_rs[$i]['s_attribute_type'], $column_display_config_rs[$i]['order_no']);
					
					if($column_display_config_rs[$i]['orderby_datatype'] === 'numeric')
						$query .= ', (ifnull(ia'.$i.'.attribute_val, ia'.$i.'.lookup_attribute_val)+0) AS '.$fieldname;
					else
						$query .= ', ifnull(ia'.$i.'.attribute_val, ia'.$i.'.lookup_attribute_val) AS '.$fieldname;
			
					if( $column_order_by == NULL && strlen($order_by)>0 && strcasecmp($order_by, $fieldname) === 0)
					{
						$column_order_by = $fieldname;
					}
				}//if($column_display_config_rs[$i]['orderby']!==FALSE)
			}
            else if($column_display_config_rs[$i]['column_type'] == 's_field_type')
			{
                if($column_display_config_rs[$i]['orderby_support_ind'] === 'Y')
				{
                	if($column_display_config_rs[$i]['s_field_type'] == 'CATEGORY')
					{
                        // add the category columns
						$query .= ',catia.lookup_attribute_val AS catia_lookup_attribute_val, catia.s_attribute_type AS catia_s_attribute_type, catia.order_no AS catia_order_no';
					}
				}
			}
		}
	}
		
	$query .= " ".
			from_and_where_clause($HTTP_VARS, $column_display_config_rs, 'LISTING');

	if($column_order_by != NULL)
	{
		$query .= ' ORDER BY '.$column_order_by.' '.$sortorder.', i.title, ii.instance_no ASC, i.s_item_type';
	}
	else if($order_by == 's_item_type')
		$query .= ' ORDER BY i.s_item_type '.$sortorder.', i.title, ii.instance_no ASC';	
	else if($order_by == 'category')
		$query .= ' ORDER BY catia_lookup_attribute_val '.$sortorder.', i.title, ii.instance_no ASC, i.s_item_type';
	else if($order_by == 'owner_id')
		$query .= ' ORDER BY ii.owner_id '.$sortorder.', i.title, ii.instance_no ASC, i.s_item_type';	
	else if($order_by == 's_status_type')
		$query .= ' ORDER BY ii.s_status_type '.$sortorder.', i.title, ii.instance_no ASC, i.s_item_type';	
	else if($order_by == 'update_on')
		$query .= ' ORDER BY ii.update_on '.$sortorder.', i.title, ii.instance_no ASC, i.s_item_type';
	else if($order_by === 'item_id')
		$query .= ' ORDER BY i.id '.$sortorder.', ii.instance_no ASC, i.s_item_type';
	else //if($order_by === 'title')
		$query .= ' ORDER BY i.title '.$sortorder.', ii.instance_no ASC, i.s_item_type';
	
	if(is_numeric($start_index) && is_numeric($items_per_page))
	{
		$query .= ' LIMIT ' .$start_index. ', ' .$items_per_page;
	}
	
	//echo "\n<code>Listing Query: $query</code>";

	$result = db_query($query);
	if($result && db_num_rows($result)>0)
		return $result;
	else
		return FALSE;          
}

/**
* 	NOTE: PRIVATE FUNCTION.

	Will return the FROM and WHERE clauses for a selection from the item table.
	
	If $owner_id defined, will limit to only items owned by owner_id
	If $s_item_type defined, will limit to only items of that type.
	If $category defined, will limit to only items of that category.
	If $letter defined will limit to item.title starting with that letter.
	If $interest_level defined will limit to items with that interest level or higher.
	
	@param $HTTP_VARS['...'] variables supported: 
		owner_id, s_item_type, s_item_type[], s_item_type_group, title, title_match, category,
		rating, attribute_type, lookup_attribute_val, attribute_val, attr_match, 
		update_on, datetimemask, update_on_days, letter, start_item_id
		s_status_type[], status_comment, not_s_status_type[], interest_level
*/
function from_and_where_clause($HTTP_VARS, $column_display_config_rs = NULL, $query_type = 'LISTING')
{
	// For checking whether count (DISTINCT ...) is supported, and thus 
	// whether we have to do any special processing!
		
	$from_r[] = 'item i';
	$from_r[] = 'item_instance ii';

	$where_r[] = 'ii.item_id = i.id';// only parent items should ever be listed.
	
	//
	// Owner restriction
	//
	if(strlen($HTTP_VARS['owner_id'])>0)
		$where_r[] = 'ii.owner_id = \''.$HTTP_VARS['owner_id'].'\'';
	else if(strlen($HTTP_VARS['not_owner_id'])>0)//For not showing current user items.
		$where_r[] = 'ii.owner_id <> \''.$HTTP_VARS['not_owner_id'].'\'';
	
	//
	// Item Type / Item Type group restriction
	//
	if(!is_array($HTTP_VARS['s_item_type']) && strlen($HTTP_VARS['s_item_type'])>0)
	{
		$where_r[] = 'i.s_item_type = \''.$HTTP_VARS['s_item_type'].'\'';
	}
	else if(strlen($HTTP_VARS['s_item_type_group'])>0)
	{
		$from_r[] = 's_item_type_group_rltshp sitgr';
		$where_r[] = 'sitgr.s_item_type = i.s_item_type';
		$where_r[] = 'sitgr.s_item_type_group = \''.$HTTP_VARS['s_item_type_group'].'\'';
	}
	else if(is_not_empty_array($HTTP_VARS['s_item_type']))
	{
		$where_r[] = 'i.s_item_type IN('.format_sql_in_clause($HTTP_VARS['s_item_type']).')';
	}
	
	$from_r[] = 's_status_type sst';
	$where_r[] = 'sst.s_status_type = ii.s_status_type';
		
	//
	// Status Type restriction
	//
	if(is_not_empty_array($HTTP_VARS['s_status_type']))
	{
		$where_r[] = 'sst.s_status_type IN('.format_sql_in_clause($HTTP_VARS['s_status_type']).')';
	}
	else if($HTTP_VARS['s_status_type'] != 'ALL' && strlen($HTTP_VARS['s_status_type'])>0)
	{	
		$where_r[] = 'sst.s_status_type = \''.$HTTP_VARS['s_status_type'].'\'';
	}
	
	// no need for such a restriction if current user is item admin
	if(!is_user_granted_permission(PERM_ITEM_ADMIN))
	{
		$where_r[] = "( sst.hidden_ind = 'N' OR ii.owner_id = '".get_opendb_session_var('user_id')."') ";
	}
	
	//
	// User and Status type restriction
	//
	if(strcmp($HTTP_VARS['owner_id'], get_opendb_session_var('user_id'))!==0) // not current user
	{
		$from_r[] = 'user u';
		$where_r[] = 'u.user_id = ii.owner_id';
		$where_r[] = 'u.active_ind = \'Y\'';
	}
	
	//
	// Status Comment restriction
	//
	if(strlen($HTTP_VARS['status_comment'])>0)
	{
		// Escape only the single quote!
		$HTTP_VARS['status_comment'] = str_replace("'","\\'", $HTTP_VARS['status_comment']);
	
		if($HTTP_VARS['status_comment_match'] != 'exact')
		{
			$parser = new BooleanParser();
			$statements = $parser->parseBooleanStatement($HTTP_VARS['status_comment']);
			if(is_array($statements))
			{
				$where_r[] = build_boolean_clause($statements, 'ii.status_comment', $HTTP_VARS['status_comment_match'], 'AND', $HTTP_VARS['status_comment_case']);
			}
		}
		else
		{
			if(is_null($HTTP_VARS['status_comment_case']))
			{
				$where_r[] = 'ii.status_comment = \''.$HTTP_VARS['status_comment'].'\'';
			}
			else
			{
				$where_r[] = 'BINARY ii.status_comment = \''.$HTTP_VARS['status_comment'].'\'';
			}
		}
	}
	
	//
	// Title restriction
	//
	if(strlen($HTTP_VARS['title'])>0)
	{
		// Escape only the single quote!
		$HTTP_VARS['title'] = str_replace("'","\\'", $HTTP_VARS['title']);
	
		if($HTTP_VARS['title_match'] != 'exact')
		{
			$parser = new BooleanParser();
			$statements = $parser->parseBooleanStatement($HTTP_VARS['title']);
			if(is_array($statements))
			{
				$where_r[] = build_boolean_clause($statements, 'i.title', $HTTP_VARS['title_match'], 'AND', $HTTP_VARS['title_case']);
			}
		}
		else
		{
			if(is_null($HTTP_VARS['title_case']))
			{
				$where_r[] = 'i.title = \''.$HTTP_VARS['title'].'\'';
			}
			else
			{
				$where_r[] = 'BINARY i.title = \''.$HTTP_VARS['title'].'\'';
			}
		}
	}
	else if(strlen($HTTP_VARS['letter'])>0)
	{
		// Numeric match.
		if($HTTP_VARS['letter'] == '#')
			$where_r[] = 'ASCII(LEFT(title,1)) BETWEEN ASCII(\'0\') AND ASCII(\'9\')';
		else
			$where_r[] = 'UPPER(LEFT(i.title,1)) = \''.strtoupper($HTTP_VARS['letter']).'\'';
	}
	
	//
	// Last Updated support
	//
	if(strlen($HTTP_VARS['update_on'])>0)
	{
		if(strlen($HTTP_VARS['datetimemask'])>0)
		{
			$timestamp = get_timestamp_for_datetime($HTTP_VARS['update_on'], $HTTP_VARS['datetimemask']);
			if($timestamp!==FALSE)
			{
				$where_r[] = 'ii.update_on >= FROM_UNIXTIME('.$timestamp.')';
			}
			else
			{
				// by default get items from 1 day ago, if update_on can not be parsed correctly.
				$where_r[] = 'TO_DAYS(ii.update_on) >= (TO_DAYS(now())-1)';
			}
		}
		else
		{
			$where_r[] = 'ii.update_on >= \''.$HTTP_VARS['update_on'].'\'';
		}
	}
	else if(is_numeric($HTTP_VARS['update_on_days']))// GIve us all records updated in the last however many days.
	{
		$where_r[] = 'TO_DAYS(ii.update_on) >= (TO_DAYS(now())-'.$HTTP_VARS['update_on_days'].')';
	}

	//
	// Item Attribute listing/restriction
	//
	if(is_array($column_display_config_rs))
	{
		for($i=0; $i<count($column_display_config_rs); $i++)
		{
			if($column_display_config_rs[$i]['column_type'] == 's_attribute_type')
			{
				if($column_display_config_rs[$i]['search_attribute_ind'] != 'y')
				{
					// either LISTING or COUNT
					if($query_type != 'COUNT')
					{
						$left_join = 'LEFT JOIN item_attribute ia'.$i.' ON '.
							'ia'.$i.'.item_id = i.id AND (ia'.$i.'.instance_no = 0 OR ia'.$i.'.instance_no = ii.instance_no) AND ia'.$i.'.s_attribute_type = \''.$column_display_config_rs[$i]['s_attribute_type'].'\' AND ia'.$i.'.attribute_no = 1';
				
						// So we can work out which search attribute types to display
						if(is_numeric($column_display_config_rs[$i]['order_no']))
						{
							$left_join .= ' AND ia'.$i.'.order_no = '.$column_display_config_rs[$i]['order_no'];
						}
						$left_join_from_r[] = $left_join;
					}
				}
				else // search attribute
				{
					$from_r[] = 'item_attribute ia'.$i;
			
					// now do the where clause.
					$where_r[] = 'ia'.$i.'.item_id = i.id AND (ia'.$i.'.instance_no = 0 OR ia'.$i.'.instance_no = ii.instance_no) AND ia'.$i.'.s_attribute_type = \''.$column_display_config_rs[$i]['s_attribute_type'].'\'';// AND ia'.$i.'.attribute_no = 1';
					
					if(strlen($column_display_config_rs[$i]['attribute_val'])>0 && 
								$column_display_config_rs[$i]['attribute_val'] != '%' &&
								$column_display_config_rs[$i]['attr_match'] != 'exact')
					{
						$parser = new BooleanParser();
						$statements = $parser->parseBooleanStatement(strtoupper(str_replace("'","\\'", $column_display_config_rs[$i]['attribute_val'])));
						if(is_array($statements))
						{
							if($column_display_config_rs[$i]['lookup_attribute_ind'] == 'Y')
							{
								$where_r[] = build_boolean_clause($statements, 'ia'.$i.'.lookup_attribute_val', 'plain', 'AND', $HTTP_VARS['attr_case']);
							}
							else
							{
								$where_r[] = build_boolean_clause($statements, 'ia'.$i.'.attribute_val', $column_display_config_rs[$i]['attr_match'], 'AND', $HTTP_VARS['attr_case']);
							}
						}
					}
					else if(strlen($column_display_config_rs[$i]['lookup_attribute_val'])>0 && 
								$column_display_config_rs[$i]['lookup_attribute_val'] != '%' &&
								$column_display_config_rs[$i]['lookup_attribute_ind'] == 'Y')
					{
						$value = str_replace("'","\\'", $column_display_config_rs[$i]['lookup_attribute_val']);
						$where_r[] = 'ia'.$i.'.lookup_attribute_val = \''.str_replace('\_','_',$value).'\'';
					}
					else if(strlen($column_display_config_rs[$i]['attribute_val'])>0 && 
							$column_display_config_rs[$i]['attribute_val'] != '%')
					{
						if(starts_with($column_display_config_rs[$i]['attribute_val'], '"') && 
										ends_with($column_display_config_rs[$i]['attribute_val'], '"'))
						{
							$column_display_config_rs[$i]['attribute_val'] = substr($column_display_config_rs[$i]['attribute_val'], 1, -1);
						}
						
						$value = strtoupper(str_replace("'","\\'", $column_display_config_rs[$i]['attribute_val']));
				
						$where_r[] = 'UPPER(ia'.$i.'.attribute_val) = \''.str_replace('\_','_',$value).'\'';
					}
					
					if(strlen($HTTP_VARS['attr_update_on'])>0)
					{
						if(strlen($HTTP_VARS['datetimemask'])>0)
						{
							$timestamp = get_timestamp_for_datetime($HTTP_VARS['attr_update_on'], $HTTP_VARS['datetimemask']);
							if($timestamp!==FALSE)
							{
								$where_r[] = 'ia'.$i.'.update_on >= FROM_UNIXTIME('.$timestamp.')';
							}
							else
							{
								// by default get items from 1 day ago, if update_on can not be parsed correctly.
								$where_r[] = 'TO_DAYS(ia'.$i.'.update_on) >= (TO_DAYS(now())-1)';
							}
						}
						else
						{
							$where_r[] = 'ia'.$i.'.update_on >= \''.$HTTP_VARS['attr_update_on'].'\'';
						}
					}
					else if(is_numeric($HTTP_VARS['attr_update_on_days']))// GIve us all records updated in the last however many days.
					{
						$where_r[] = 'TO_DAYS(ia'.$i.'.update_on) >= (TO_DAYS(now())-'.$HTTP_VARS['attr_update_on_days'].')';
					}
				}
			}
            else if($column_display_config_rs[$i]['column_type'] == 's_field_type')
			{
               	if($column_display_config_rs[$i]['s_field_type'] == 'CATEGORY')
				{
					$from_r[] = 's_item_attribute_type catsiat';
					$from_r[] = 's_attribute_type catsat';
					$where_r[] = 'catsiat.s_item_type = i.s_item_type AND catsat.s_attribute_type = catsiat.s_attribute_type AND catsat.s_field_type = \'CATEGORY\'';

					$left_join_clause = 'LEFT JOIN item_attribute catia ON '.
							'catia.item_id = i.id AND (catia.instance_no = 0 OR catia.instance_no = ii.instance_no) AND catia.s_attribute_type = catsiat.s_attribute_type AND catia.order_no = catsiat.order_no';

					if(strlen($HTTP_VARS['category'])>0 ||
							(strcasecmp($HTTP_VARS['attr_match'], 'category')===0 &&
								strlen($HTTP_VARS['attribute_val'])>0))// Support specifying $attribute_val for $category where $attr_match=="category"!
					{
						// If item_type && item_type_group are not set!
						if(strlen($HTTP_VARS['attribute_type'])>0 && !is_array($HTTP_VARS['s_item_type']) && strlen($HTTP_VARS['s_item_type'])==0 && strlen($HTTP_VARS['s_item_type_group'])==0)
						{
                                 $where_r[] = 'catsat.s_attribute_type = \''.$HTTP_VARS['attribute_type'].'\'';
						}

						// Escape single quotes only.
						$value = strtoupper(str_replace("'","\\'", ifempty($HTTP_VARS['category'], $HTTP_VARS['attribute_val'])));
						$where_r[] = 'UPPER(catia.lookup_attribute_val) = \''.str_replace('\_','_',$value).'\'';
					}
					else
					{
				        $left_join_clause .= ' AND catia.attribute_no = 1';
					}

					$left_join_from_r[] = $left_join_clause;
				}
			}
		}
	}

	// If attribute_val specified without a attribute_type, then do a loose join to item_attribute table,
	// only on attribute_val column.
	if(strlen($HTTP_VARS['attribute_type'])==0 &&
			(strlen($HTTP_VARS['attribute_val'])>0 ||
			strlen($HTTP_VARS['attr_update_on'])>0 ||
			strlen($HTTP_VARS['attr_update_on_days'])>0))
	{
		$from_r[] = 'item_attribute ia';
				
		// now do the where clause.
		$where_r[] = 'ia.item_id = i.id '; //AND ia.attribute_no = 1';
		
		if($HTTP_VARS['attr_match'] != 'exact')
		{
			$parser = new BooleanParser();
			$statements = $parser->parseBooleanStatement(strtoupper(str_replace("'","\\'", $HTTP_VARS['attribute_val'])));
			if(is_array($statements))
			{
				if(is_lookup_attribute_type($HTTP_VARS['attribute_type']))
				{
					$where_r[] = build_boolean_clause($statements, 'ia.lookup_attribute_val', 'plain', 'AND', $HTTP_VARS['attr_case']);
				}
				else
				{
					$where_r[] = build_boolean_clause($statements, 'ia.attribute_val', $HTTP_VARS['attr_match'], 'AND', $HTTP_VARS['attr_case']);
				}
			}
		}
		else// attr_match = 'exact'
		{
			if(is_lookup_attribute_type($HTTP_VARS['attribute_type']))
			{
				$value = str_replace("'","\\'", $HTTP_VARS['attribute_val']);
				
				$where_r[] = 'ia.lookup_attribute_val = \''.str_replace('\_','_',$value).'\'';
			}
			else
			{
				$value = str_replace("'","\\'", $HTTP_VARS['attribute_val']);
				
				if(is_null($HTTP_VARS['attr_case']))
				{
					$where_r[] = '( ia.attribute_val = \''.str_replace('\_','_',$value).'\' OR '.
						'ia.attribute_val LIKE \'% '.$value.' %\' OR '.
						'ia.attribute_val LIKE \''.$value.' %\' OR '.
						'ia.attribute_val LIKE \'% '.$value.'\')';
				}
				else
				{
					$where_r[] = '( BINARY ia.attribute_val = \''.str_replace('\_','_',$value).'\' OR '.
						'ia.attribute_val LIKE BINARY \'% '.$value.' %\' OR '.
						'ia.attribute_val LIKE BINARY \''.$value.' %\' OR '.
						'ia.attribute_val LIKE BINARY \'% '.$value.'\')';

				}
			}
		}
		
		if(strlen($HTTP_VARS['attr_update_on'])>0)
		{
			if(strlen($HTTP_VARS['datetimemask'])>0)
			{
				$timestamp = get_timestamp_for_datetime($HTTP_VARS['attr_update_on'], $HTTP_VARS['datetimemask']);
				if($timestamp!==FALSE)
				{
					$where_r[] = 'ia.update_on >= FROM_UNIXTIME('.$timestamp.')';
				}
				else
				{
					// by default get items from 1 day ago, if update_on can not be parsed correctly.
					$where_r[] = 'TO_DAYS(ia.update_on) >= (TO_DAYS(now())-1)';
				}
			}
			else
			{
				$where_r[] = 'ia.update_on >= \''.$HTTP_VARS['attr_update_on'].'\'';
			}
		}
		else if(is_numeric($HTTP_VARS['attr_update_on_days']))// GIve us all records updated in the last however many days.
		{
			$where_r[] = 'TO_DAYS(ia.update_on) >= (TO_DAYS(now())-'.$HTTP_VARS['attr_update_on_days'].')';
		}
	}
	
	//
	// Review restrictions
	//
	if(strlen($HTTP_VARS['rating'])>0)
	{
		$where_r[] = 'r.item_id = i.id AND r.rating >= '.$HTTP_VARS['rating'];
		$from_r[] = 'review r';
	}
	
	//
	// Item ID range restriction (Used by Import script)
	//
	if(strlen($HTTP_VARS['item_id_range'])>0)
	{
		$where_r[] = 'i.id IN ('.expand_number_range($HTTP_VARS['item_id_range']).')';
	}

	//
	// Interest level restrictions
	//
	if(strlen($HTTP_VARS['interest_level'])>0)
	{
		$where_r[] = "it.item_id = ii.item_id AND it.instance_no = ii.instance_no AND it.user_id = '".get_opendb_session_var('user_id')."'".
					 " AND it.level >= ".$HTTP_VARS['interest_level'];
		$from_r[] = "user_item_interest it";
	}

	//
	// Now build the SQL query
	//	
	if(is_array($from_r))
	{
		$from_clause = '';
		for($i=0; $i<count($from_r); $i++)
		{
			if(strlen($from_clause)>0)
				$from_clause .= ', ';
			$from_clause .= $from_r[$i];
		}
		$query .= 'FROM ('.$from_clause.') ';
	}
	
	if(is_array($left_join_from_r))
	{
		$left_join_from_clause = '';
		for($i=0; $i<count($left_join_from_r); $i++)
		{
			if(strlen($left_join_from_clause)>0)
				$left_join_from_clause .= ' ';
			$left_join_from_clause .= $left_join_from_r[$i];
		}
		
		$query .= $left_join_from_clause.' ';
	}
	
	if(is_array($where_r))
	{
		$where_clause = '';
		for($i=0; $i<count($where_r); $i++)
		{
			if(strlen($where_clause)>0)
				$where_clause .= ' AND ';
			$where_clause .= $where_r[$i];
		}
		$query .= 'WHERE '.$where_clause;
	}

	return $query;
}

//
// If successful will return the new ID for the item, otherwise will return FALSE.
//
function insert_item($s_item_type, $title)
{
	if(strlen($title)>0)
	{
		$title = addslashes(replace_newlines(trim(strip_tags($title))));
		
		$query = "INSERT INTO item (s_item_type, title)".				   
				" VALUES ('$s_item_type', '$title')";

		$insert = db_query($query);
		if ($insert && db_affected_rows() > 0)
		{
			$new_item_id = db_insert_id();
			opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($s_item_type, $title));
			return $new_item_id;
		}
		else
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($s_item_type, $title));
			return FALSE;
		}
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($s_item_type, $title));
		return FALSE;
	}		
}

function update_item($item_id, $title)
{
	if(strlen($title)>0)
	{
        $query = "UPDATE item ".
				"SET title = '".addslashes(replace_newlines(trim(strip_tags($title))))."'".
				"WHERE id = '$item_id'";

		$update = db_query($query);
		// We should not treat updates that were not actually updated because value did not change as failures.
		$rows_affected = db_affected_rows();
		if ($update && $rows_affected !== -1)
		{
			if($rows_affected>0)
				opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id, $title));
			return TRUE;
		}
		else
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $title));
			return FALSE;
		}
	}
}

/**
	Delete item and return boolean indicating success or failure.
	
	This function does not check for any dependencies.
*/	
function delete_item($item_id)
{
	$query ="DELETE FROM item WHERE id='".$item_id."'";
	$delete = db_query($query);
	if($delete && db_affected_rows() > 0)
	{
		opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id));
		return TRUE;
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id));
		return FALSE;
	}
}

/*
* Delete item_attributes, item.
* 
* Assumes instances have been deleted.
*/
function delete_item_cascaded($item_id)
{
	if(db_query("LOCK TABLES item WRITE, item_attribute WRITE, item_instance WRITE"))
	{
		if(delete_item_attributes($item_id, NULL, NULL, NULL))
		{
			if(delete_item($item_id))
			{
				// Can't forget to unlock table.
				db_query("UNLOCK TABLES");
				return TRUE;
			}
			else
			{
				// Can't forget to unlock table.
				db_query("UNLOCK TABLES");
					
				return FALSE;
			}
		}
		else
		{
			// Can't forget to unlock table.
			db_query("UNLOCK TABLES");
					
			return FALSE;
		}
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id));
		return FALSE;
	}
}

/**
* Used by all insert/update item_instance functions to make sure the data is valid.  Will
* also update $status_comment / $borrow_duration and set them to a legal value for the
* specified $s_status_type
*/
function validate_item_instance_fields($s_status_type, &$status_comment, &$borrow_duration)
{
	// At this point, a specific $s_status_type MUST be supplied.
	if(strlen($s_status_type)>0)
	{
		$status_type_r = fetch_status_type_r($s_status_type);
	}
		
	if(is_not_empty_array($status_type_r))	
	{
		// A $borrow_duration explicitly set to FALSE, is
		// an indication that nothing should be done with it.
		if($borrow_duration !== FALSE && $borrow_duration !== NULL)//if already null, no need to check again.
		{
			// Ensure we have a valid $borrow_duration
			if(is_numeric($borrow_duration))//column cannot handle more than 999
			{
				if($borrow_duration > 999)
					$borrow_duration = '999';
			}
			else
			{
				$borrow_duration = NULL;
			}
		}
		
		$status_comment = addslashes(substr(replace_newlines(trim(strip_tags($status_comment))),0,255));
		
		return TRUE;
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, 'Invalid Status Type', array($s_status_type));
		
		return FALSE;
	}
}

/**
	For subsequent item_instance inserts.

	Does not support $s_status_type = 'W' specific functionality.

*/
function insert_item_instance($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration, $owner_id)
{
	if(validate_item_instance_fields($s_status_type, $status_comment, $borrow_duration))
	{
		$item_instance_locked = FALSE;
		
		// No need to lock if new item, as no other item_instances will
		// be assigned to it yet!
		if(!is_numeric($instance_no))
		{
			if(db_query("LOCK TABLES item_instance WRITE"))
			{	
				$item_instance_locked = TRUE;
				
				// If not specified, work out the next one along.
				$instance_no = fetch_max_instance_no($item_id);
				if(is_numeric($instance_no))
				{
					// Add 1 to $instance_no
					$instance_no = (int)$instance_no;
					$instance_no++;
				}
				else // new item
				{
					$instance_no = 1;
				}
			}
			else
			{
				opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration, $owner_id));
				return FALSE;
			}
		}
		
		//Either the instance_no was specified to begin with, or the LOCK TABLES and fetch_max_instance_no call worked.
		$query = "INSERT INTO item_instance(item_id, instance_no, owner_id, borrow_duration, s_status_type, status_comment)".
				"VALUES ('$item_id','$instance_no','$owner_id',".(is_numeric($borrow_duration)?"'$borrow_duration'":"NULL").",UPPER('".$s_status_type."'),'$status_comment')";
				
		$insert = db_query($query);
		if ($insert && db_affected_rows() > 0)
		{
			// Can't forget to unlock table.
			if($item_instance_locked)
			{
				db_query("UNLOCK TABLES");
			}
				
			opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration, $owner_id));
			return $instance_no;
		}
		else
		{
			// Can't forget to unlock table.
			if($item_instance_locked)
			{
				db_query("UNLOCK TABLES");
			}
			
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration, $owner_id));
			return FALSE;
		}			
	}
	else //if(validate_item_instance_fields($s_status_type, $borrow_duration))
	{
		return FALSE;
	}
}

/**
	@param $borrow_duration If set to FALSE, no update will occur.  If not numeric, will be
	set to NULL otherwise.
	
	@param $status_comment If set to FALSE, no update will occur.  If not numeric, will be
	set to NULL otherwise.
*/
function update_item_instance($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration)
{
	if(validate_item_instance_fields($s_status_type, $status_comment, $borrow_duration))
	{
		$query = "UPDATE item_instance SET ";
	
		// If $borrow_duration explicitly set to FALSE, then no update should occur!
		if($borrow_duration !== FALSE)
		{
			$query .= "borrow_duration = ".(is_numeric($borrow_duration)?"'$borrow_duration'":"NULL").", ";
		}
			
		if($status_comment!==FALSE)
			$query .= "status_comment = '$status_comment', ";
	
		$query .= "s_status_type = UPPER('".$s_status_type."') ".
			"WHERE item_id = '$item_id' AND instance_no = '$instance_no'";

		$update = db_query($query);
		
		// We should not treat updates that were not actually updated because value did not change as failures.
		$rows_affected = db_affected_rows();
		if($update && $rows_affected !== -1)
		{
			if($rows_affected>0)
				opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration));
			return TRUE;
		}
		else
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $s_status_type, $status_comment, $borrow_duration));
			return FALSE;
		}
	}
	else //if(validate_item_instance_fields($s_status_type, $borrow_duration))
	{	
		return FALSE;
	}
}

/**
	@param $borrow_duration If set to FALSE, no update will occur.  If not numeric, will be
	set to NULL otherwise.
	
	@param $status_comment If set to FALSE, no update will occur.  If not numeric, will be
	set to NULL otherwise.
*/
function update_item_instance_owner($item_id, $instance_no, $old_owner_id, $owner_id)
{
	$query = "UPDATE item_instance SET owner_id = '$owner_id' "
			."WHERE item_id = '$item_id' AND instance_no = '$instance_no'";

	$update = db_query($query);
	
	// We should not treat updates that were not actually updated because value did not change as failures.
	$rows_affected = db_affected_rows();
	if($update && $rows_affected !== -1)
	{
		if($rows_affected>0)
			opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id, $instance_no, $old_owner_id, $owner_id));
		return TRUE;
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $old_owner_id, $owner_id));
		return FALSE;
	}
}

//
// Delete item and return boolean indicating success or failure.
//
function delete_item_instance($item_id, $instance_no)
{
	// remove all child related item instance relationships only - not the actual instances themselves.
	delete_item_instance_relationships($item_r['item_id'], $item_r['instance_no']);
		
	if(!is_exists_related_item_instance_relationship($item_r['item_id'], $item_r['instance_no']))
	{
		$query = "DELETE FROM item_instance WHERE item_id = '".$item_id."' AND instance_no = '$instance_no'";
		$delete = db_query($query);
		if(db_affected_rows() > 0)
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no));
			return TRUE;
		}
		else
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no));
			return FALSE;
		}
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, 'Instance is referenced in at least one item instance relationship', array($item_id, $instance_no));
		return FALSE;
	}
}

function insert_item_instance_relationships($item_id, $related_item_id, $related_instance_no)
{
	$instance_no_r = NULL;
	$results = fetch_item_instance_rs($item_id);
	if($results)
	{
		while($item_instance_r = db_fetch_assoc($results))
		{
			$instance_no_r[] = $item_instance_r['instance_no'];
		}
		db_free_result($results);
	}

	// todo - should this be locked?!
	if(is_array($instance_no_r))
	{
		while(list(,$instance_no) = each($instance_no_r))
		{
			insert_item_instance_relationship($item_id, $instance_no, $related_item_id, $related_instance_no);
		}
	}
}

function insert_item_instance_relationship($item_id, $instance_no, $related_item_id, $related_instance_no)
{
	if(is_numeric($item_id) && is_numeric($instance_no) && is_numeric($related_item_id) && is_numeric($related_instance_no))
	{
		$query = "INSERT INTO item_instance_relationship(item_id, instance_no, related_item_id, related_instance_no)".
				"VALUES ($item_id, $instance_no, $related_item_id, $related_instance_no)";
		
		$insert = db_query($query);
		if ($insert && db_affected_rows() > 0)
		{
			$sequence_number = db_insert_id();
			
			opendb_logger(OPENDB_LOG_INFO, __FILE__, __FUNCTION__, NULL, array($item_id, $instance_no, $related_item_id, $related_instance_no));
			return $sequence_number;
		}
		else
		{
			opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $related_item_id, $related_instance_no));
			return FALSE;
		}
	}
	else
	{
		return FALSE;			
	}
}

function delete_item_instance_relationships($item_id, $instance_no = NULL)
{
	$query = "DELETE FROM item_instance WHERE item_id = '".$item_id."'";
	
	if(is_numeric($instance_no))
	{
		$query .= " AND instance_no = '$instance_no'";
	}
	
	$delete = db_query($query);
	if(db_affected_rows() > 0)
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no));
		return TRUE;
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no));
		return FALSE;
	}
}

/**
 * Take item_id and get DISTINCT list of related items, and copy for new instance.
 *
 * @param unknown_type $item_id
 * @param unknown_type $instance_no
 */
function copy_related_item_instance_relationships($item_id, $instance_no)
{
	$item_instance_rs = NULL;
	$results = fetch_item_instance_relationship_rs($item_id);
	if($results)
	{
		while($item_instance_r = db_fetch_assoc($results))
		{
			if($item_instance_r['instance_no'] != $instance_no)
			{
				$item_instance_rs[] = $item_instance_r;
			}
		}
		db_free_result($results);
	}
	
	if(is_array($item_instance_rs))
	{
		while(list(,$item_instance_r) = each($item_instance_rs))
		{
			insert_item_instance_relationship($item_id, $instance_no, $item_instance_r['item_id'], $item_instance_r['instance_no']);
		}
	}
}

function delete_related_item_instance_relationship($item_id, $instance_no, $parent_item_id, $parent_instance_no)
{
	$query = "DELETE FROM item_instance_relationship 
			WHERE related_item_id = '".$item_id."' AND 
				related_instance_no = $instance_no AND
				item_id = $parent_item_id AND
				instance_no = $parent_instance_no";
	
	$delete = db_query($query);
	if(db_affected_rows() > 0)
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $parent_item_id, $parent_instance_no));
		return TRUE;
	}
	else
	{
		opendb_logger(OPENDB_LOG_ERROR, __FILE__, __FUNCTION__, db_error(), array($item_id, $instance_no, $parent_item_id, $parent_instance_no));
		return FALSE;
	}
}
?>
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