Marcus Povey <marcus@dushka.co.uk>

* Moved Query object et al to their own file

git-svn-id: https://code.elgg.org/elgg/trunk@785 36083f99-b078-4883-b0ff-0f9b5a30f544

2 files changed, 757 insertions, 743 deletions

diff --git a/engine/lib/database.php b/engine/lib/database.php
index aea310841..55d2533c2 100644
--- a/engine/lib/database.php
+++ b/engine/lib/database.php
@@ -11,749 +11,6 @@
 	 * @copyright Curverider Ltd 2008

 	 * @link http://elgg.org/

 	 */
-
-	/**
-	 * @class QueryComponent Query component superclass.
-	 * Component of a query.
-	 * @author Marcus Povey
-	 */
-	abstract class QueryComponent 
-	{
-		/**
-		 * Associative array of fields and values
-		 */ 
-		private $fields;
-
-		function __construct()
-		{
-			$this->fields = array(); 
-		}
-		
-		/**
-		 * Class member get overloading
-		 *
-		 * @param string $name
-		 * @return mixed
-		 */
-		function __get($name) {
-			return $this->fields[$name];
-		}
-		
-		/**
-		 * Class member set overloading
-		 *
-		 * @param string $name
-		 * @param mixed $value
-		 * @return void
-		 */
-		function __set($name, $value) {
-			$this->fields[$name] = $value;
-			
-			return true;
-		}	
-	}
-	
-	/**
-	 * @class SelectFieldQueryComponent Class representing a select field.
-	 * This class represents a select field component.
-	 * @author Marcus Povey
-	 */
-	class SelectFieldQueryComponent extends QueryComponent 
-	{
-		/**
-		 * Construct a select field component
-		 * 
-		 * @param string $table The table containing the field.
-		 * @param string $field The field or "*"
-		 */
-		function __construct($table, $field) 
-		{
-			global $CONFIG;
-			
-			$this->table = $CONFIG->dbprefix . sanitise_string($table);
-			$this->field = sanitise_string($field);
-		}
-		
-		function __toString() 
-		{
-			return "{$this->table}.{$this->field}";
-		}
-	}
-	
-	/**
-	 * @class LimitOffsetQueryComponent
-	 * Limit and offset clauses of a query.
-	 * @author Marcus Povey
-	 */
-	class LimitOffsetQueryComponent extends QueryComponent
-	{
-		/**
-		 * Specify a limit and an offset.
-		 * 
-		 * @param int $limit The limit.
-		 * @param int $offset The offset.
-		 */
-		function __construct($limit = 25, $offset = 0)
-		{
-			$this->limit = (int)$limit;
-			$this->offset = (int)$offset;
-		}
-		
-		function __toString()
-		{
-			return "limit {$this->offset}, {$this->limit}";
-		}
-	}
-	
-	/**
-	 * @class OrderQueryComponent
-	 * Order the query results.
-	 * @author Marcus Povey
-	 */
-	class OrderQueryComponent extends QueryComponent
-	{
-		function __construct($table, $field, $order = "asc")
-		{
-			global $CONFIG;
-			
-			$this->table = $CONFIG->dbprefix . sanitise_string($table);
-			$this->field = sanitise_string($field);
-			$this->order = sanitise_string($order);
-		}
-		
-		function __toString()
-		{
-			return "order by {$this->table}.{$this->field} {$this->order}";
-		}
-	}
-	
-	/**
-	 * @class TableQueryComponent
-	 * List of tables to select from or insert into.
-	 * @author Marcus Povey
-	 */
-	class TableQueryComponent extends QueryComponent
-	{
-		function __construct($table)
-		{
-			global $CONFIG;
-			
-			$this->table = $CONFIG->dbprefix . sanitise_string($table);
-		}
-		
-		function __toString()
-		{
-			return $this->table;
-		}
-	}
-	
-	/**
-	 * @class AccessControlQueryComponent
-	 * Access control component.
-	 * @author Marcus Povey
-	 */
-	class AccessControlQueryComponent extends QueryComponent
-	{
-		/**
-		 * Construct the ACL.
-		 * 
-		 * @param string $acl_table The table where the access control field is.
-		 * @param string $acl_field The field containing the access control.
-		 * @param string $object_owner_table The table containing the owner information for the stuff you're retrieving.
-		 * @param string $object_owner_id_field The field in $object_owner_table containing the owner information
-		 */
-		function __construct($acl_table = "entities", $acl_field = "access_id", $object_owner_table = "entities", $object_owner_id_field = "owner_guid")
-		{
-			global $CONFIG;
-			
-			$this->acl_table = $CONFIG->dbprefix . sanitise_string($acl_table);
-			$this->acl_field = sanitise_string($acl_field);
-			$this->object_owner_table = $CONFIG->dbprefix . sanitise_string($object_owner_table);
-			$this->object_owner_id_field = sanitise_string($object_owner_id_field);
-		}
-		
-		function __toString()
-		{
-			$access = get_access_list();
-			
-			return "and ({$this->acl_table}.{$this->acl_field} in {$access} or ({$this->acl_table}.{$this->acl_field} = 0 and {$this->object_owner_table}.{$this->object_owner_id_field} = {$_SESSION['id']}))";
-		}
-	}
-	
-	/**
-	 * @class JoinQueryComponent Join query.
-	 * Represents a join query.
-	 * @author Marcus Povey
-	 */
-	class JoinQueryComponent extends QueryComponent
-	{
-		/**
-		 * Construct a join query.
-		 * @param string $table Table one to join...
-		 * @param string $field Field 1 with...
-		 * @param string $table2 Table 2 ... 
-		 * @param string $field2 Field...
-		 * @param string $operator Using this operator
-		 */
-		function __construct($table1, $field1, $table2, $field2, $operator = "=") 
-		{
-			global $CONFIG;
-			
-			$this->table1 = $CONFIG->dbprefix . sanitise_string($table1);
-			$this->field1 = sanitise_string($field1);
-			$this->table2 = $CONFIG->dbprefix . sanitise_string($table2);
-			$this->field2 = sanitise_string($field2);
-			$this->operator = sanitise_string($operator);
-		}
-		
-		function __toString() 
-		{
-			return "join {$this->table2} on {$this->$table}.{$this->$field} {$this->$operator} {$this->$table2}.{$this->$field2}";
-		}
-	}
-	
-	/**
-	 * @class SetQueryComponent Set query.
-	 * Represents an update set query.
-	 * @author Marcus Povey
-	 */
-	class SetQueryComponent extends QueryComponent
-	{
-		/**
-		 * Construct a setting query
-		 *
-		 * @param string $table The table to modify
-		 * @param string $field The field to modify
-		 * @param mixed $value The value to set it to
-		 */
-		function __construct($table, $field, $value)
-		{
-			global $CONFIG;
-			
-		 	$this->table = $CONFIG->dbprefix . sanitise_string($table);
-		 	$this->field = sanitise_string($field);
-		 	if (is_numeric($value))
-		 		$this->value = (int)$value;
-		 	else
-		 		$this->value = "'".sanitise_string($value)."'";
-		}
-		
-		function __toString() 
-		{
-			return "{$this->table}.{$this->field}={$this->value}";
-		}
-	}
-	
-	/**
-	 * @class WhereQueryComponent
-	 * A component of a where query.
-	 * @author Marcus Povey
-	 */
-	class WhereQueryComponent extends QueryComponent
-	{
-		/**
-		 * A where query.
-		 * 
-		 * @param string $left_table The table on the left of the operator
-		 * @param string $left_field The left field
-		 * @param string $operator The operator eg "=" or "<"
-		 * @param string $right_table The table on the right of the operator
-		 * @param string $right_field The right field
-		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
-		 */
-		function __construct($left_table, $left_field, $operator, $right_table, $right_field, $link_operator = "and")
-		{
-			global $CONFIG;
-			
-			$this->link_operator = sanitise_string($link_operator);
-		 	$this->left_table = $CONFIG->dbprefix . sanitise_string($left_table);
-		 	$this->left_field = sanitise_string($left_field);
-		 	$this->operator = sanitise_string($operator);
-		 	$this->right_table = $CONFIG->dbprefix . sanitise_string($right_table);
-		 	$this->right_field = sanitise_string($right_field);
-		}
-		
-		/**
-		 * Return the SQL without the link operator.
-		 */
-		public function toStringNoLink()
-		{
-			return "{$this->left_table }.{$this->left_field} {$this->operator} {$this->right_table}.{$this->right_field}";
-		}
-		
-		function __toString() 
-		{
-			return "{$this->link_operator} " . $this->toStringNoLink();
-		}
-	}
-	
-	/**
-	 * @class WhereStaticQueryComponent
-	 * A component of a where query where there is no right hand table, rather a static value.
-	 * @author Marcus Povey
-	 */
-	class WhereStaticQueryComponent extends WhereQueryComponent
-	{
-		/**
-		 * A where query.
-		 * 
-		 * @param string $left_table The table on the left of the operator
-		 * @param string $left_field The left field
-		 * @param string $operator The operator eg "=" or "<"
-		 * @param string $value The value
-		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
-		 */
-		function __construct($left_table, $left_field, $operator, $value, $link_operator = "and")
-		{
-			global $CONFIG;
-			
-			$this->link_operator = sanitise_string($link_operator);
-		 	$this->left_table = $CONFIG->dbprefix . sanitise_string($left_table);
-		 	$this->left_field = sanitise_string($left_field);
-		 	$this->operator = sanitise_string($operator);
-		 	if (is_numeric($value))
-		 		$this->value = (int)$value;
-		 	else
-		 		$this->value = "'".sanitise_string($value)."'";
-		}
-		
-		/**
-		 * Return the SQL without the link operator.
-		 */
-		public function toStringNoLink()
-		{
-			return "{$this->left_table }.{$this->left_field} {$this->operator} {$this->value}";
-		}
-	}
-	
-	/**
-	 * @class WhereSetQueryComponent
-	 * A where query that may contain other where queries (in brackets).
-	 * @author Marcus Povey
-	 */
-	class WhereSetQueryComponent extends WhereQueryComponent
-	{
-		/**
-		 * Construct a subset of wheres.
-		 *
-		 * @param array $wheres An array of WhereQueryComponent 
-		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
-		 */
-		function __construct(array $wheres, $link_operator = "and")
-		{
-			$this->link_operator = sanitise_string($link_operator);
-			$this->wheres = $wheres;
-		}
-		
-		public function toStringNoLink()
-		{
-			$cnt = 0;
-			$string = " (";
-			foreach ($this->wheres as $where) {
-				if (!($where instanceof WhereQueryComponent))
-					throw new DatabaseException("Where set contains non WhereQueryComponent");
-				
-				if (!$cnt)
-					$string.= $where->toStringNoLink();
-				else
-					$string.=" $where ";
-				
-				$cnt ++;			
-			}
-			$string .= ")";
-			
-			return $string;
-		}
-	}
-	
-	/**
-	 * @class QueryTypeQueryComponent
-	 * What type of query is this?
-	 * @author Marcus Povey
-	 */
-	abstract class QueryTypeQueryComponent extends QueryComponent 
-	{
-		function __toString()
-		{
-			return $this->query_type; 
-		}
-	}
-	
-	/**
-	 * @class SelectQueryTypeQueryComponent
-	 * A select query.
-	 * @author Marcus Povey
-	 */
-	class SelectQueryTypeQueryComponent extends QueryTypeQueryComponent 
-	{
-		function __construct() 
-		{
-			$this->query_type = "select";	
-		}
-	}
-	
-	/**
-	 * @class InsertQueryTypeQueryComponent
-	 * An insert query.
-	 * @author Marcus Povey
-	 */
-	class InsertQueryTypeQueryComponent extends QueryTypeQueryComponent 
-	{
-		function __construct() 
-		{
-			$this->query_type = "insert into";	
-		}
-	}
-	
-	/**
-	 * @class DeleteQueryTypeQueryComponent
-	 * A delete query.
-	 * @author Marcus Povey
-	 */
-	class DeleteQueryTypeQueryComponent extends QueryTypeQueryComponent 
-	{
-		function __construct() 
-		{
-			$this->query_type = "delete from";	
-		}
-	}
-	
-	/**
-	 * @class UpdateQueryTypeQueryComponent
-	 * An update query.
-	 * @author Marcus Povey
-	 */
-	class UpdateQueryTypeQueryComponent extends QueryTypeQueryComponent 
-	{
-		function __construct() 
-		{
-			$this->query_type = "update";	
-		}
-	}
-	
-	/**
-	 * @class Query
-	 * This class provides a framework to construct complex queries in a safe environment.
-	 * 
-	 * @author Marcus Povey
-	 */
-	class Query
-	{
-		
-		/// The limit of the query
-		private $limit_and_offset; 
-		
-		/// Fields to return on a query
-		private $fields;
-		
-		/// Tables to use in a from query
-		private $tables;
-		
-		/// Join tables
-		private $joins;
-		
-		/// Set values 
-		private $sets;
-		
-		/// Where query
-		private $where;
-		
-		/// Order by
-		private $order;
-		
-		/// The query type
-		private $query_type;
-		
-		/// ACL
-		private $access_control;
-		
-		/**
-		 * Construct query & initialise variables
-		 */
-		function __construct() 
-		{
-			$this->fields = array();
-			$this->tables = array();
-			$this->joins = array();
-			$this->where = array();
-			$this->sets = array();
-			
-			$this->setQueryType(new SelectQueryTypeQueryComponent());
-		}
-		
-		public function setLimitAndOffset(LimitOffsetQueryComponent $component) { $this->limit_and_offset = $component; }
-		
-		public function setSelectField(SelectFieldQueryComponent $component) 
-		{
-			$this->fields = array();
-			return $this->addSelectField($component);
-		}
-		
-		public function addSelectField(SelectFieldQueryComponent $component) { $this->fields[] = $component; }
-		
-		public function addJoin(JoinQueryComponent $component) { $this->joins[] = $component; }
-		
-		public function addSet(SetQueryComponent $component) { $this->sets[] = $component; }
-		
-		public function setQueryType(QueryTypeQueryComponent $component) { $this->query_type = $component; }
-		
-		public function setOrder(OrderQueryComponent $component) { $this->order = $component; }
-		
-		public function addTable(TableQueryComponent $component) { $this->tables[] = $component; }
-		
-		public function addWhere(WhereQueryComponent $component) { $this->where[] = $component; }
-		
-		public function setAccessControl(AccessControlQueryComponent $component) { $this->access_control = $component; }
-		
-		public function __toString()
-		{
-			global $CONFIG;
-			
-			$sql = "";
-			
-			try
-			{ 
-				// Query prefix & fields
-				if (!empty($this->query_type))
-				{
-					$sql .= "{$this->query_type} ";
-					
-					if (!empty($this->fields))
-					{
-						$fields = "";
-						
-						foreach ($this->fields as $field)
-							$fields .= "$field";	
-						
-						$sql .= " $fields from ";
-					}
-					else
-						throw new DatabaseException("Fields missing on a select style query");
-				}
-				else
-					throw new DatabaseException("Unrecognised or unspecified query type.");
-						
-				// Tables
-				if (!empty($this->tables)) 
-				{
-					foreach($this->tables as $table) 
-						$sql .= "$table, ";
-						
-					$sql = trim($sql, ", ");
-				}
-				else
-					throw new DatabaseException("No tables specified for query.");
-				
-				// Joins on select queries
-				if ($this->query_type->query_type == 'select') 
-				{
-					if (!empty($this->joins)) 
-					{	
-						foreach($this->joins as $join) 
-							$sql .= "$join ";
-					}
-				}
-				
-				// Setting values
-				if (
-					($this->query_type->query_type == 'update') || 
-					($this->query_type->query_type == 'insert')
-				) 
-				{
-					$sql .= "set ";
-					
-					foreach ($this->sets as $set)
-						$sql .= "$set, ";
-						
-					$sql = trim($sql, ", ") . " ";
-				}
-				
-				// Where
-				if (!empty($this->where))
-				{
-					$sql .= " where 1 ";
-					
-					foreach ($this->where as $where)
-						$sql .= "$where ";
-				}
-	
-				// Access control
-				if (!empty($this->access_control)) 
-				{
-				
-					// Catch missing Where
-					if (empty($this->where))
-						$sql .= " where 1 ";
-					
-					$sql .= "{$this->access_control} ";
-				} 
-				else
-					throw new DatabaseException("No access control was provided on query");
-					
-				// Order by
-				if (!empty($this->order))
-					$sql .= "{$this->order} ";
-					
-				// Limits
-				if (!empty($this->limit_and_offset))
-					$sql .= "{$this->limit_and_offset} ";
-				
-				
-				
-			} catch (Exception $e) {
-				trigger_error($e, E_USER_WARNING);
-			}
-			
-					
-			return $sql;
-		}
-		
-	}
-	
-	/**
-	 * @class SimpleQuery
-	 * A wrapper for Query which provides simple interface for common functions.
-	 * @author Marcus Povey
-	 */
-	class SimpleQuery extends Query
-	{
-		function __construct() 
-		{
-			parent::__construct();
-			
-			// Set a default query type (select)
-			$this->simpleQueryType();
-			
-			// Set a default access control
-			$this->simpleAccessControl();
-			
-			// Set default limit and offset
-			$this->simpleLimitAndOffset();
-		}
-		
-		/**
-		 * Set the query type.
-		 * 
-		 * @param string $type The type of search - available are "select", "update", "delete", "insert".
-		 */
-		public function simpleQueryType($type = "select")
-		{
-			$type = strtolower(sanitise_string($type));
-			
-			switch ($type)
-			{
-				case "insert" :
-					return $this->setQueryType(InsertQueryTypeQueryComponent()); 
-				break;
-				case "delete" : 
-					return $this->setQueryType(DeleteQueryTypeQueryComponent());
-				break;
-				case "update" :
-					 return $this->setQueryType(UpdateQueryTypeQueryComponent());
-				break;
-				default: return $this->setQueryType(SelectQueryTypeQueryComponent());
-			}
-		}
-
-		/**
-		 * Set a field to query in a select statement.
-		 * 
-		 * @param string $table Table to query.
-		 * @param string $field Field in that table.
-		 */
-		public function simpleSelectField($table, $field) { return $this->setSelectField(new SelectFieldQueryComponent($table, $field)); }
-		
-		/**
-		 * Add a select field to query in a select statement.
-		 * 
-		 * @param string $table Table to query.
-		 * @param string $field Field in that table. 
-		 */
-		public function simpleAddSelectField($table, $field) { return $this->addSelectField(new SelectFieldQueryComponent($table, $field)); }
-		
-		/**
-		 * Add a set value to an update query.
-		 * 
-		 * @param string $table The table to update.
-		 * @param string $field The field in the table.
-		 * @param mixed $value The value to set it to.
-		 */
-		public function simpleSet($table, $field, $value) { return $this->addSet(new SetQueryComponent($table, $field, $value)); }
-		
-		/**
-		 * Add a join to the table.
-		 * 
-		 * @param string $table Table one to join...
-		 * @param string $field Field 1 with...
-		 * @param string $table2 Table 2 ... 
-		 * @param string $field2 Field...
-		 * @param string $operator Using this operator 
-		 */
-		public function simpleJoin($table1, $field1, $table2, $field2, $operator = "=") { return $this->addJoin(new JoinQueryComponent($table1, $field1, $table2, $field2, $operator)); }
-		
-		/**
-		 * Add a table to the query.
-		 * 
-		 * @param string $table The table.
-		 */
-		public function simpleTable($table) { return $this->addTable(new TableQueryComponent($table)); }
-
-		/**
-		 * Compare one table/field to another table/field.
-		 * 
-		 * @param string $left_table The table on the left of the operator
-		 * @param string $left_field The left field
-		 * @param string $operator The operator eg "=" or "<"
-		 * @param string $right_table The table on the right of the operator
-		 * @param string $right_field The right field
-		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
-		 */
-		public function simpleWhereOnTable($left_table, $left_field, $operator, $right_table, $right_field, $link_operator = "and") { return $this->addWhere(new WhereQueryComponent($left_table, $left_field, $operator, $right_table, $right_field, $link_operator)); }
-		
-		/**
-		 * Compare one table/field to a value.
-		 * 
-		 * @param string $left_table The table on the left of the operator
-		 * @param string $left_field The left field
-		 * @param string $operator The operator eg "=" or "<"
-		 * @param string $value The value
-		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
-		 */
-		public function simpleWhereOnValue($left_table, $left_field, $operator, $value, $link_operator = "and") { return $this->addWhere(new WhereStaticQueryComponent($left_table, $left_field, $operator, $value, $link_operator)); }
-		
-		/**
-		 * Set access control.
-		 * 
-		 * @param string $acl_table The table where the access control field is.
-		 * @param string $acl_field The field containing the access control.
-		 * @param string $object_owner_id_field The field in $object_owner_table containing the owner information.
-		 */
-		public function simpleAccessControl($acl_table = "entities", $acl_field = "access_id", $object_owner_id_field = "owner_guid") { return $this->setAccessControl(new AccessControlQueryComponent($acl_table, $acl_field, $acl_table, $object_owner_id_field)); }
-
-		/**
-		 * Set the limit and offset.
-		 * 
-		 * @param int $limit The limit.
-		 * @param int $offset The offset.
-		 */
-		public function simpleLimitAndOffset($limit = 25, $offset = 0) { return $this->setLimitAndOffset(new LimitOffsetQueryComponent($limit, $offset)); }
-		
-		/**
-		 * Set the order query.
-		 * 
-		 * @param string $table The table to query
-		 * @param string $field The field to query
-		 * @param string $order Order the query
-		 */
-		public function simpleOrder($table, $field, $order = "desc") 
-		{
-			$table = sanitise_string($table);
-			$field = sanitise_string($field);
-			$order = strtolower(sanitise_string($order));
-			 
-			return $this->setOrder(new OrderQueryComponent($table, $field, $order)); break;
-		}
-	}
 	

 	/**

 	 * Connect to the database server and use the Elgg database for a particular database link

diff --git a/engine/lib/query.php b/engine/lib/query.php
new file mode 100644
index 000000000..8b6df5c8b
--- /dev/null
+++ b/engine/lib/query.php
@@ -0,0 +1,757 @@
+<?php
+	/**
+	 * Elgg database query
+	 * Contains a wrapper for performing database queries in a structured way.
+	 * 
+	 * @package Elgg
+	 * @subpackage Core
+	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
+	 * @author Marcus Povey
+	 * @copyright Curverider Ltd 2008
+	 * @link http://elgg.org/
+	 */
+
+
+	/**
+	 * @class QueryComponent Query component superclass.
+	 * Component of a query.
+	 * @author Marcus Povey
+	 */
+	abstract class QueryComponent 
+	{
+		/**
+		 * Associative array of fields and values
+		 */ 
+		private $fields;
+
+		function __construct()
+		{
+			$this->fields = array(); 
+		}
+		
+		/**
+		 * Class member get overloading
+		 *
+		 * @param string $name
+		 * @return mixed
+		 */
+		function __get($name) {
+			return $this->fields[$name];
+		}
+		
+		/**
+		 * Class member set overloading
+		 *
+		 * @param string $name
+		 * @param mixed $value
+		 * @return void
+		 */
+		function __set($name, $value) {
+			$this->fields[$name] = $value;
+			
+			return true;
+		}	
+	}
+	
+	/**
+	 * @class SelectFieldQueryComponent Class representing a select field.
+	 * This class represents a select field component.
+	 * @author Marcus Povey
+	 */
+	class SelectFieldQueryComponent extends QueryComponent 
+	{
+		/**
+		 * Construct a select field component
+		 * 
+		 * @param string $table The table containing the field.
+		 * @param string $field The field or "*"
+		 */
+		function __construct($table, $field) 
+		{
+			global $CONFIG;
+			
+			$this->table = $CONFIG->dbprefix . sanitise_string($table);
+			$this->field = sanitise_string($field);
+		}
+		
+		function __toString() 
+		{
+			return "{$this->table}.{$this->field}";
+		}
+	}
+	
+	/**
+	 * @class LimitOffsetQueryComponent
+	 * Limit and offset clauses of a query.
+	 * @author Marcus Povey
+	 */
+	class LimitOffsetQueryComponent extends QueryComponent
+	{
+		/**
+		 * Specify a limit and an offset.
+		 * 
+		 * @param int $limit The limit.
+		 * @param int $offset The offset.
+		 */
+		function __construct($limit = 25, $offset = 0)
+		{
+			$this->limit = (int)$limit;
+			$this->offset = (int)$offset;
+		}
+		
+		function __toString()
+		{
+			return "limit {$this->offset}, {$this->limit}";
+		}
+	}
+	
+	/**
+	 * @class OrderQueryComponent
+	 * Order the query results.
+	 * @author Marcus Povey
+	 */
+	class OrderQueryComponent extends QueryComponent
+	{
+		function __construct($table, $field, $order = "asc")
+		{
+			global $CONFIG;
+			
+			$this->table = $CONFIG->dbprefix . sanitise_string($table);
+			$this->field = sanitise_string($field);
+			$this->order = sanitise_string($order);
+		}
+		
+		function __toString()
+		{
+			return "order by {$this->table}.{$this->field} {$this->order}";
+		}
+	}
+	
+	/**
+	 * @class TableQueryComponent
+	 * List of tables to select from or insert into.
+	 * @author Marcus Povey
+	 */
+	class TableQueryComponent extends QueryComponent
+	{
+		function __construct($table)
+		{
+			global $CONFIG;
+			
+			$this->table = $CONFIG->dbprefix . sanitise_string($table);
+		}
+		
+		function __toString()
+		{
+			return $this->table;
+		}
+	}
+	
+	/**
+	 * @class AccessControlQueryComponent
+	 * Access control component.
+	 * @author Marcus Povey
+	 */
+	class AccessControlQueryComponent extends QueryComponent
+	{
+		/**
+		 * Construct the ACL.
+		 * 
+		 * @param string $acl_table The table where the access control field is.
+		 * @param string $acl_field The field containing the access control.
+		 * @param string $object_owner_table The table containing the owner information for the stuff you're retrieving.
+		 * @param string $object_owner_id_field The field in $object_owner_table containing the owner information
+		 */
+		function __construct($acl_table = "entities", $acl_field = "access_id", $object_owner_table = "entities", $object_owner_id_field = "owner_guid")
+		{
+			global $CONFIG;
+			
+			$this->acl_table = $CONFIG->dbprefix . sanitise_string($acl_table);
+			$this->acl_field = sanitise_string($acl_field);
+			$this->object_owner_table = $CONFIG->dbprefix . sanitise_string($object_owner_table);
+			$this->object_owner_id_field = sanitise_string($object_owner_id_field);
+		}
+		
+		function __toString()
+		{
+			$access = get_access_list();
+			
+			return "and ({$this->acl_table}.{$this->acl_field} in {$access} or ({$this->acl_table}.{$this->acl_field} = 0 and {$this->object_owner_table}.{$this->object_owner_id_field} = {$_SESSION['id']}))";
+		}
+	}
+	
+	/**
+	 * @class JoinQueryComponent Join query.
+	 * Represents a join query.
+	 * @author Marcus Povey
+	 */
+	class JoinQueryComponent extends QueryComponent
+	{
+		/**
+		 * Construct a join query.
+		 * @param string $table Table one to join...
+		 * @param string $field Field 1 with...
+		 * @param string $table2 Table 2 ... 
+		 * @param string $field2 Field...
+		 * @param string $operator Using this operator
+		 */
+		function __construct($table1, $field1, $table2, $field2, $operator = "=") 
+		{
+			global $CONFIG;
+			
+			$this->table1 = $CONFIG->dbprefix . sanitise_string($table1);
+			$this->field1 = sanitise_string($field1);
+			$this->table2 = $CONFIG->dbprefix . sanitise_string($table2);
+			$this->field2 = sanitise_string($field2);
+			$this->operator = sanitise_string($operator);
+		}
+		
+		function __toString() 
+		{
+			return "join {$this->table2} on {$this->$table}.{$this->$field} {$this->$operator} {$this->$table2}.{$this->$field2}";
+		}
+	}
+	
+	/**
+	 * @class SetQueryComponent Set query.
+	 * Represents an update set query.
+	 * @author Marcus Povey
+	 */
+	class SetQueryComponent extends QueryComponent
+	{
+		/**
+		 * Construct a setting query
+		 *
+		 * @param string $table The table to modify
+		 * @param string $field The field to modify
+		 * @param mixed $value The value to set it to
+		 */
+		function __construct($table, $field, $value)
+		{
+			global $CONFIG;
+			
+		 	$this->table = $CONFIG->dbprefix . sanitise_string($table);
+		 	$this->field = sanitise_string($field);
+		 	if (is_numeric($value))
+		 		$this->value = (int)$value;
+		 	else
+		 		$this->value = "'".sanitise_string($value)."'";
+		}
+		
+		function __toString() 
+		{
+			return "{$this->table}.{$this->field}={$this->value}";
+		}
+	}
+	
+	/**
+	 * @class WhereQueryComponent
+	 * A component of a where query.
+	 * @author Marcus Povey
+	 */
+	class WhereQueryComponent extends QueryComponent
+	{
+		/**
+		 * A where query.
+		 * 
+		 * @param string $left_table The table on the left of the operator
+		 * @param string $left_field The left field
+		 * @param string $operator The operator eg "=" or "<"
+		 * @param string $right_table The table on the right of the operator
+		 * @param string $right_field The right field
+		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
+		 */
+		function __construct($left_table, $left_field, $operator, $right_table, $right_field, $link_operator = "and")
+		{
+			global $CONFIG;
+			
+			$this->link_operator = sanitise_string($link_operator);
+		 	$this->left_table = $CONFIG->dbprefix . sanitise_string($left_table);
+		 	$this->left_field = sanitise_string($left_field);
+		 	$this->operator = sanitise_string($operator);
+		 	$this->right_table = $CONFIG->dbprefix . sanitise_string($right_table);
+		 	$this->right_field = sanitise_string($right_field);
+		}
+		
+		/**
+		 * Return the SQL without the link operator.
+		 */
+		public function toStringNoLink()
+		{
+			return "{$this->left_table }.{$this->left_field} {$this->operator} {$this->right_table}.{$this->right_field}";
+		}
+		
+		function __toString() 
+		{
+			return "{$this->link_operator} " . $this->toStringNoLink();
+		}
+	}
+	
+	/**
+	 * @class WhereStaticQueryComponent
+	 * A component of a where query where there is no right hand table, rather a static value.
+	 * @author Marcus Povey
+	 */
+	class WhereStaticQueryComponent extends WhereQueryComponent
+	{
+		/**
+		 * A where query.
+		 * 
+		 * @param string $left_table The table on the left of the operator
+		 * @param string $left_field The left field
+		 * @param string $operator The operator eg "=" or "<"
+		 * @param string $value The value
+		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
+		 */
+		function __construct($left_table, $left_field, $operator, $value, $link_operator = "and")
+		{
+			global $CONFIG;
+			
+			$this->link_operator = sanitise_string($link_operator);
+		 	$this->left_table = $CONFIG->dbprefix . sanitise_string($left_table);
+		 	$this->left_field = sanitise_string($left_field);
+		 	$this->operator = sanitise_string($operator);
+		 	if (is_numeric($value))
+		 		$this->value = (int)$value;
+		 	else
+		 		$this->value = "'".sanitise_string($value)."'";
+		}
+		
+		/**
+		 * Return the SQL without the link operator.
+		 */
+		public function toStringNoLink()
+		{
+			return "{$this->left_table }.{$this->left_field} {$this->operator} {$this->value}";
+		}
+	}
+	
+	/**
+	 * @class WhereSetQueryComponent
+	 * A where query that may contain other where queries (in brackets).
+	 * @author Marcus Povey
+	 */
+	class WhereSetQueryComponent extends WhereQueryComponent
+	{
+		/**
+		 * Construct a subset of wheres.
+		 *
+		 * @param array $wheres An array of WhereQueryComponent 
+		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
+		 */
+		function __construct(array $wheres, $link_operator = "and")
+		{
+			$this->link_operator = sanitise_string($link_operator);
+			$this->wheres = $wheres;
+		}
+		
+		public function toStringNoLink()
+		{
+			$cnt = 0;
+			$string = " (";
+			foreach ($this->wheres as $where) {
+				if (!($where instanceof WhereQueryComponent))
+					throw new DatabaseException("Where set contains non WhereQueryComponent");
+				
+				if (!$cnt)
+					$string.= $where->toStringNoLink();
+				else
+					$string.=" $where ";
+				
+				$cnt ++;			
+			}
+			$string .= ")";
+			
+			return $string;
+		}
+	}
+	
+	/**
+	 * @class QueryTypeQueryComponent
+	 * What type of query is this?
+	 * @author Marcus Povey
+	 */
+	abstract class QueryTypeQueryComponent extends QueryComponent 
+	{
+		function __toString()
+		{
+			return $this->query_type; 
+		}
+	}
+	
+	/**
+	 * @class SelectQueryTypeQueryComponent
+	 * A select query.
+	 * @author Marcus Povey
+	 */
+	class SelectQueryTypeQueryComponent extends QueryTypeQueryComponent 
+	{
+		function __construct() 
+		{
+			$this->query_type = "select";	
+		}
+	}
+	
+	/**
+	 * @class InsertQueryTypeQueryComponent
+	 * An insert query.
+	 * @author Marcus Povey
+	 */
+	class InsertQueryTypeQueryComponent extends QueryTypeQueryComponent 
+	{
+		function __construct() 
+		{
+			$this->query_type = "insert into";	
+		}
+	}
+	
+	/**
+	 * @class DeleteQueryTypeQueryComponent
+	 * A delete query.
+	 * @author Marcus Povey
+	 */
+	class DeleteQueryTypeQueryComponent extends QueryTypeQueryComponent 
+	{
+		function __construct() 
+		{
+			$this->query_type = "delete from";	
+		}
+	}
+	
+	/**
+	 * @class UpdateQueryTypeQueryComponent
+	 * An update query.
+	 * @author Marcus Povey
+	 */
+	class UpdateQueryTypeQueryComponent extends QueryTypeQueryComponent 
+	{
+		function __construct() 
+		{
+			$this->query_type = "update";	
+		}
+	}
+	
+	/**
+	 * @class Query
+	 * This class provides a framework to construct complex queries in a safe environment.
+	 * 
+	 * @author Marcus Povey
+	 */
+	class Query
+	{
+		
+		/// The limit of the query
+		private $limit_and_offset; 
+		
+		/// Fields to return on a query
+		private $fields;
+		
+		/// Tables to use in a from query
+		private $tables;
+		
+		/// Join tables
+		private $joins;
+		
+		/// Set values 
+		private $sets;
+		
+		/// Where query
+		private $where;
+		
+		/// Order by
+		private $order;
+		
+		/// The query type
+		private $query_type;
+		
+		/// ACL
+		private $access_control;
+		
+		/**
+		 * Construct query & initialise variables
+		 */
+		function __construct() 
+		{
+			$this->fields = array();
+			$this->tables = array();
+			$this->joins = array();
+			$this->where = array();
+			$this->sets = array();
+			
+			$this->setQueryType(new SelectQueryTypeQueryComponent());
+		}
+		
+		public function setLimitAndOffset(LimitOffsetQueryComponent $component) { $this->limit_and_offset = $component; }
+		
+		public function setSelectField(SelectFieldQueryComponent $component) 
+		{
+			$this->fields = array();
+			return $this->addSelectField($component);
+		}
+		
+		public function addSelectField(SelectFieldQueryComponent $component) { $this->fields[] = $component; }
+		
+		public function addJoin(JoinQueryComponent $component) { $this->joins[] = $component; }
+		
+		public function addSet(SetQueryComponent $component) { $this->sets[] = $component; }
+		
+		public function setQueryType(QueryTypeQueryComponent $component) { $this->query_type = $component; }
+		
+		public function setOrder(OrderQueryComponent $component) { $this->order = $component; }
+		
+		public function addTable(TableQueryComponent $component) { $this->tables[] = $component; }
+		
+		public function addWhere(WhereQueryComponent $component) { $this->where[] = $component; }
+		
+		public function setAccessControl(AccessControlQueryComponent $component) { $this->access_control = $component; }
+		
+		public function __toString()
+		{
+			global $CONFIG;
+			
+			$sql = "";
+			
+			try
+			{ 
+				// Query prefix & fields
+				if (!empty($this->query_type))
+				{
+					$sql .= "{$this->query_type} ";
+					
+					if (!empty($this->fields))
+					{
+						$fields = "";
+						
+						foreach ($this->fields as $field)
+							$fields .= "$field";	
+						
+						$sql .= " $fields from ";
+					}
+					else
+						throw new DatabaseException("Fields missing on a select style query");
+				}
+				else
+					throw new DatabaseException("Unrecognised or unspecified query type.");
+						
+				// Tables
+				if (!empty($this->tables)) 
+				{
+					foreach($this->tables as $table) 
+						$sql .= "$table, ";
+						
+					$sql = trim($sql, ", ");
+				}
+				else
+					throw new DatabaseException("No tables specified for query.");
+				
+				// Joins on select queries
+				if ($this->query_type->query_type == 'select') 
+				{
+					if (!empty($this->joins)) 
+					{	
+						foreach($this->joins as $join) 
+							$sql .= "$join ";
+					}
+				}
+				
+				// Setting values
+				if (
+					($this->query_type->query_type == 'update') || 
+					($this->query_type->query_type == 'insert')
+				) 
+				{
+					$sql .= "set ";
+					
+					foreach ($this->sets as $set)
+						$sql .= "$set, ";
+						
+					$sql = trim($sql, ", ") . " ";
+				}
+				
+				// Where
+				if (!empty($this->where))
+				{
+					$sql .= " where 1 ";
+					
+					foreach ($this->where as $where)
+						$sql .= "$where ";
+				}
+	
+				// Access control
+				if (!empty($this->access_control)) 
+				{
+				
+					// Catch missing Where
+					if (empty($this->where))
+						$sql .= " where 1 ";
+					
+					$sql .= "{$this->access_control} ";
+				} 
+				else
+					throw new DatabaseException("No access control was provided on query");
+					
+				// Order by
+				if (!empty($this->order))
+					$sql .= "{$this->order} ";
+					
+				// Limits
+				if (!empty($this->limit_and_offset))
+					$sql .= "{$this->limit_and_offset} ";
+				
+				
+				
+			} catch (Exception $e) {
+				trigger_error($e, E_USER_WARNING);
+			}
+			
+					
+			return $sql;
+		}
+		
+	}
+	
+	/**
+	 * @class SimpleQuery
+	 * A wrapper for Query which provides simple interface for common functions.
+	 * @author Marcus Povey
+	 */
+	class SimpleQuery extends Query
+	{
+		function __construct() 
+		{
+			parent::__construct();
+			
+			// Set a default query type (select)
+			$this->simpleQueryType();
+			
+			// Set a default access control
+			$this->simpleAccessControl();
+			
+			// Set default limit and offset
+			$this->simpleLimitAndOffset();
+		}
+		
+		/**
+		 * Set the query type.
+		 * 
+		 * @param string $type The type of search - available are "select", "update", "delete", "insert".
+		 */
+		public function simpleQueryType($type = "select")
+		{
+			$type = strtolower(sanitise_string($type));
+			
+			switch ($type)
+			{
+				case "insert" :
+					return $this->setQueryType(InsertQueryTypeQueryComponent()); 
+				break;
+				case "delete" : 
+					return $this->setQueryType(DeleteQueryTypeQueryComponent());
+				break;
+				case "update" :
+					 return $this->setQueryType(UpdateQueryTypeQueryComponent());
+				break;
+				default: return $this->setQueryType(SelectQueryTypeQueryComponent());
+			}
+		}
+
+		/**
+		 * Set a field to query in a select statement.
+		 * 
+		 * @param string $table Table to query.
+		 * @param string $field Field in that table.
+		 */
+		public function simpleSelectField($table, $field) { return $this->setSelectField(new SelectFieldQueryComponent($table, $field)); }
+		
+		/**
+		 * Add a select field to query in a select statement.
+		 * 
+		 * @param string $table Table to query.
+		 * @param string $field Field in that table. 
+		 */
+		public function simpleAddSelectField($table, $field) { return $this->addSelectField(new SelectFieldQueryComponent($table, $field)); }
+		
+		/**
+		 * Add a set value to an update query.
+		 * 
+		 * @param string $table The table to update.
+		 * @param string $field The field in the table.
+		 * @param mixed $value The value to set it to.
+		 */
+		public function simpleSet($table, $field, $value) { return $this->addSet(new SetQueryComponent($table, $field, $value)); }
+		
+		/**
+		 * Add a join to the table.
+		 * 
+		 * @param string $table Table one to join...
+		 * @param string $field Field 1 with...
+		 * @param string $table2 Table 2 ... 
+		 * @param string $field2 Field...
+		 * @param string $operator Using this operator 
+		 */
+		public function simpleJoin($table1, $field1, $table2, $field2, $operator = "=") { return $this->addJoin(new JoinQueryComponent($table1, $field1, $table2, $field2, $operator)); }
+		
+		/**
+		 * Add a table to the query.
+		 * 
+		 * @param string $table The table.
+		 */
+		public function simpleTable($table) { return $this->addTable(new TableQueryComponent($table)); }
+
+		/**
+		 * Compare one table/field to another table/field.
+		 * 
+		 * @param string $left_table The table on the left of the operator
+		 * @param string $left_field The left field
+		 * @param string $operator The operator eg "=" or "<"
+		 * @param string $right_table The table on the right of the operator
+		 * @param string $right_field The right field
+		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
+		 */
+		public function simpleWhereOnTable($left_table, $left_field, $operator, $right_table, $right_field, $link_operator = "and") { return $this->addWhere(new WhereQueryComponent($left_table, $left_field, $operator, $right_table, $right_field, $link_operator)); }
+		
+		/**
+		 * Compare one table/field to a value.
+		 * 
+		 * @param string $left_table The table on the left of the operator
+		 * @param string $left_field The left field
+		 * @param string $operator The operator eg "=" or "<"
+		 * @param string $value The value
+		 * @param string $link_operator How this where clause links with the previous clause, eg. "and" "or"
+		 */
+		public function simpleWhereOnValue($left_table, $left_field, $operator, $value, $link_operator = "and") { return $this->addWhere(new WhereStaticQueryComponent($left_table, $left_field, $operator, $value, $link_operator)); }
+		
+		/**
+		 * Set access control.
+		 * 
+		 * @param string $acl_table The table where the access control field is.
+		 * @param string $acl_field The field containing the access control.
+		 * @param string $object_owner_id_field The field in $object_owner_table containing the owner information.
+		 */
+		public function simpleAccessControl($acl_table = "entities", $acl_field = "access_id", $object_owner_id_field = "owner_guid") { return $this->setAccessControl(new AccessControlQueryComponent($acl_table, $acl_field, $acl_table, $object_owner_id_field)); }
+
+		/**
+		 * Set the limit and offset.
+		 * 
+		 * @param int $limit The limit.
+		 * @param int $offset The offset.
+		 */
+		public function simpleLimitAndOffset($limit = 25, $offset = 0) { return $this->setLimitAndOffset(new LimitOffsetQueryComponent($limit, $offset)); }
+		
+		/**
+		 * Set the order query.
+		 * 
+		 * @param string $table The table to query
+		 * @param string $field The field to query
+		 * @param string $order Order the query
+		 */
+		public function simpleOrder($table, $field, $order = "desc") 
+		{
+			$table = sanitise_string($table);
+			$field = sanitise_string($field);
+			$order = strtolower(sanitise_string($order));
+			 
+			return $this->setOrder(new OrderQueryComponent($table, $field, $order)); break;
+		}
+	}
+?>
\ No newline at end of file