diff --git a/classes/Collection.php b/classes/Collection.php
index 848bbe398..c111f644b 100644
--- a/classes/Collection.php
+++ b/classes/Collection.php
@@ -32,6 +32,10 @@
  */
 class CollectionCore implements Iterator, ArrayAccess, Countable
 {
+	const LEFT_JOIN = 1;
+	const INNER_JOIN = 2;
+	const LEFT_OUTER_JOIN = 3;
+
 	/**
 	 * @var string Object class name
 	 */
@@ -75,6 +79,10 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	protected $fields = array();
 	protected $alias = array();
 	protected $alias_iterator = 0;
+	protected $join_list = array();
+	protected $association_definition = array();
+
+	const LANG_ALIAS = 'l';
 
 	/**
 	 * @param string $classname
@@ -87,25 +95,45 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 
 		$this->definition = ObjectModel::getDefinition($this->classname);
 		if (!isset($this->definition['table']))
-			throw new PrestashopException('Miss table in definition for class '.$this->classname);
+			throw new PrestaShopException('Miss table in definition for class '.$this->classname);
 		else if (!isset($this->definition['primary']))
-			throw new PrestashopException('Miss primary in definition for class '.$this->classname);
+			throw new PrestaShopException('Miss primary in definition for class '.$this->classname);
 
-		$alias = $this->generateAlias();
 		$this->query = new DbQuery();
-		$this->query->select($alias.'.*');
-		$this->query->from($this->definition['table'], $alias);
+	}
 
-		// If multilang, create association to lang table
-		// @todo create virtual association with lang in ObjectModel::getDefinition()
-		if (isset($this->definition['multilang']) && $this->definition['multilang'])
+	/**
+	 * Join current entity to an associated entity
+	 *
+	 * @param $association Association name
+	 * @param string $on
+	 * @param int $type
+	 * @return Collection
+	 */
+	public function join($association, $on = '', $type = null)
+	{
+		if (!$association)
+			return;
+
+		if (!isset($this->join_list[$association]))
 		{
-			$lang_alias = $this->generateAlias('@lang');
-			$this->query->select($lang_alias.'.*');
-			$this->query->leftJoin($this->definition['table'].'_lang', $lang_alias, $alias.'.'.$this->definition['primary'].' = '.$lang_alias.'.'. $this->definition['primary']);
-			if ($this->id_lang)
-				$this->query->where($lang_alias.'.id_lang = '.(int)$this->id_lang);
+			$definition = $this->getDefinition($association);
+			$on = '{'.$definition['asso']['complete_field'].'} = {'.$definition['asso']['complete_foreign_field'].'}';
+			$type = self::LEFT_JOIN;
+			$this->join_list[$association] = array(
+				'table' =>	($definition['is_lang']) ? $definition['table'].'_lang' : $definition['table'],
+				'alias' => $this->generateAlias($association),
+				'on' => array(),
+			);
 		}
+
+		if ($on)
+			$this->join_list[$association]['on'][] = $this->parseFields($on);
+
+		if ($type)
+			$this->join_list[$association]['type'] = $type;
+
+		return $this;
 	}
 
 	/**
@@ -114,10 +142,14 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	 * @param string $field Field name
 	 * @param string $operator List of operators : =, !=, <>, <, <=, >, >=, like, notlike, regexp, notregexp
 	 * @param mixed $value
+	 * @param string $type where|having
 	 * @return Collection
 	 */
-	public function where($field, $operator, $value)
+	public function where($field, $operator, $value, $method = 'where')
 	{
+		if ($method != 'where' && $method != 'having')
+			throw new PrestaShopException('Bad method argument for where() method (should be "where" or "having")');
+
 		// Create WHERE clause with an array value (IN, NOT IN)
 		if (is_array($value))
 		{
@@ -125,17 +157,17 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 			{
 				case '=' :
 				case 'in' :
-					$this->query->where($this->parseField($field).' IN('.implode(', ', $this->formatValue($value, $field)).')');
+					$this->query->$method($this->parseField($field).' IN('.implode(', ', $this->formatValue($value, $field)).')');
 				break;
 
 				case '!=' :
 				case '<>' :
 				case 'notin' :
-					$this->query->where($this->parseField($field).' NOT IN('.implode(', ', $this->formatValue($value, $field)).')');
+					$this->query->$method($this->parseField($field).' NOT IN('.implode(', ', $this->formatValue($value, $field)).')');
 				break;
 
 				default :
-					throw new PrestashopException('Operator not supported for array value');
+					throw new PrestaShopException('Operator not supported for array value');
 			}
 		}
 		// Create WHERE clause
@@ -152,19 +184,19 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 				case '<=' :
 				case 'like' :
 				case 'regexp' :
-					$this->query->where($this->parseField($field).' '.$operator.' '.$this->formatValue($value, $field));
+					$this->query->$method($this->parseField($field).' '.$operator.' '.$this->formatValue($value, $field));
 				break;
 
 				case 'notlike' :
-					$this->query->where($this->parseField($field).' NOT LIKE '.$this->formatValue($value, $field));
+					$this->query->$method($this->parseField($field).' NOT LIKE '.$this->formatValue($value, $field));
 				break;
 
 				case 'notregexp' :
-					$this->query->where($this->parseField($field).' NOT REGEXP '.$this->formatValue($value, $field));
+					$this->query->$method($this->parseField($field).' NOT REGEXP '.$this->formatValue($value, $field));
 				break;
 
 				default :
-					throw new PrestashopException('Operator not supported');
+					throw new PrestaShopException('Operator not supported');
 			}
 		}
 
@@ -175,6 +207,7 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	 * Add WHERE restriction on query using real SQL syntax
 	 *
 	 * @param string $sql
+	 * @return Collection
 	 */
 	public function sqlWhere($sql)
 	{
@@ -182,6 +215,31 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 		return $this;
 	}
 
+	/**
+	 * Add HAVING restriction on query
+	 *
+	 * @param string $field Field name
+	 * @param string $operator List of operators : =, !=, <>, <, <=, >, >=, like, notlike, regexp, notregexp
+	 * @param mixed $value
+	 * @return Collection
+	 */
+	public function having($field, $operator, $value)
+	{
+		return $this->where($field, $operator, $value, 'having');
+	}
+
+	/**
+	 * Add HAVING restriction on query using real SQL syntax
+	 *
+	 * @param string $sql
+	 * @return Collection
+	 */
+	public function sqlHaving($sql)
+	{
+		$this->query->having($this->parseFields($sql));
+		return $this;
+	}
+
 	/**
 	 * Add ORDER BY restriction on query
 	 *
@@ -193,11 +251,23 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	{
 		$order = strtolower($order);
 		if ($order != 'asc' && $order != 'desc')
-			throw new PrestashopException('Order must be asc or desc');
+			throw new PrestaShopException('Order must be asc or desc');
 		$this->query->orderBy($this->parseField($field).' '.$order);
 		return $this;
 	}
 
+	/**
+	 * Add ORDER BY restriction on query using real SQL syntax
+	 *
+	 * @param string $sql
+	 * @return Collection
+	 */
+	public function sqlOrderBy($sql)
+	{
+		$this->query->orderBy($this->parseFields($sql));
+		return $this;
+	}
+
 	/**
 	 * Add GROUP BY restriction on query
 	 *
@@ -210,6 +280,18 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 		return $this;
 	}
 
+	/**
+	 * Add GROUP BY restriction on query using real SQL syntax
+	 *
+	 * @param string $sql
+	 * @return Collection
+	 */
+	public function sqlGroupBy($sql)
+	{
+		$this->query->orderBy($this->parseFields($sql));
+		return $this;
+	}
+
 	/**
 	 * Launch sql query to create collection of objects
 	 *
@@ -222,6 +304,39 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 			return $this;
 		$this->is_hydrated = true;
 
+		$alias = $this->generateAlias();
+		//$this->query->select($alias.'.*');
+		$this->query->from($this->definition['table'], $alias);
+
+		// If multilang, create association to lang table
+		if (!empty($this->definition['multilang']))
+		{
+			$this->join(self::LANG_ALIAS);
+			if ($this->id_lang)
+				$this->where(self::LANG_ALIAS.'.id_lang', '=', $this->id_lang);
+		}
+
+		// Add join clause
+		foreach ($this->join_list as $data)
+		{
+			$on = '('.implode(') AND (', $data['on']).')';
+			switch ($data['type'])
+			{
+				case self::LEFT_JOIN :
+					$this->query->leftJoin($data['table'], $data['alias'], $on);
+				break;
+
+				case self::INNER_JOIN :
+					$this->query->innerJoin($data['table'], $data['alias'], $on);
+				break;
+
+				case self::LEFT_OUTER_JOIN :
+					$this->query->leftOuterJoin($data['table'], $data['alias'], $on);
+				break;
+			}
+		}
+
+		// Shall we display query for debug ?
 		if ($display_query)
 			echo $this->query.'<br />';
 
@@ -334,7 +449,7 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	{
 		$this->getAll();
 		if (!isset($this->results[$offset]))
-			throw new PrestashopException('Unknown offset '.$offset.' for collection '.$this->classname);
+			throw new PrestaShopException('Unknown offset '.$offset.' for collection '.$this->classname);
 		return $this->results[$offset];
 	}
 
@@ -348,7 +463,7 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	public function offsetSet($offset, $value)
 	{
 		if (!$value instanceof $this->classname)
-			throw new PrestashopException('You cannot add an element which is not an instance of '.$this->classname);
+			throw new PrestaShopException('You cannot add an element which is not an instance of '.$this->classname);
 
 		$this->getAll();
 		if (is_null($offset))
@@ -369,6 +484,69 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 		unset($this->results[$offset]);
 	}
 
+	/**
+	 * Get definition of an association
+	 *
+	 * @param string $association
+	 * @return array
+	 */
+	protected function getDefinition($association)
+	{
+		if (!$association)
+			return $this->definition;
+
+		if (!isset($this->association_definition[$association]))
+		{
+			$definition = $this->definition;
+			$split = explode('.', $association);
+			$is_lang = false;
+			for ($i = 0, $total_association = count($split); $i < $total_association; $i++)
+			{
+				$asso = $split[$i];
+
+				// Check is current association exists in current definition
+				if (!isset($definition['associations'][$asso]))
+					throw new PrestaShopException('Association '.$asso.' not found for class '.$this->definition['classname']);
+				$current_def = $definition['associations'][$asso];
+
+				// Special case for lang alias
+				if ($asso == self::LANG_ALIAS)
+				{
+					$is_lang = true;
+					break;
+				}
+
+				$classname = (isset($current_def['object'])) ? $current_def['object'] : Tools::toCamelCase($asso, true);
+				$definition = ObjectModel::getDefinition($classname);
+			}
+
+			// Get definition of associated entity and add information on current association
+			$current_def['name'] = $asso;
+			if (!isset($current_def['object']))
+				$current_def['object'] = Tools::toCamelCase($asso, true);
+			if (!isset($current_def['field']))
+				$current_def['field'] = 'id_'.$asso;
+			if (!isset($current_def['foreign_field']))
+				$current_def['foreign_field'] = 'id_'.$asso;
+			if ($total_association > 1)
+			{
+				unset($split[$total_association - 1]);
+				$current_def['complete_field'] = implode('.', $split).'.'.$current_def['field'];
+			}
+			else
+				$current_def['complete_field'] = $current_def['field'];
+			$current_def['complete_foreign_field'] = $association.'.'.$current_def['field'];
+
+			$definition['is_lang'] = $is_lang;
+			$definition['asso'] = $current_def;
+			$this->association_definition[$association] = $definition;
+		}
+		else
+			$definition = $this->association_definition[$association];
+
+		return $definition;
+	}
+
 	/**
 	 * Parse all fields with {field} syntax in a string
 	 *
@@ -400,6 +578,7 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 	 *
 	 * @param mixed $value
 	 * @param string $field Field name
+	 * @return mixed
 	 */
 	protected function formatValue($value, $field)
 	{
@@ -425,20 +604,36 @@ class CollectionCore implements Iterator, ArrayAccess, Countable
 		if (!isset($this->fields[$field]))
 		{
 			$split = explode('.', $field);
-			$association = '';
-			$definition = ObjectModel::getDefinition($this->classname);
-			for ($i = 0, $total_association = count($split) - 1; $i < $total_association; $i++)
+			$total = count($split);
+			if ($total > 1)
 			{
-				// @todo association
+				$fieldname = $split[$total - 1];
+				unset($split[$total - 1]);
+				$association = implode('.', $split);
+			}
+			else
+			{
+				$fieldname = $field;
+				$association = '';
 			}
 
-			$fieldname = $split[$i];
-			if ($fieldname == $definition['primary'])
+			$definition = $this->getDefinition($association);
+			if ($association && !isset($this->join_list[$association]))
+				$this->join($association);
+
+			if ($fieldname == $definition['primary'] || (!empty($definition['is_lang']) && $fieldname == 'id_lang'))
 				$type = ObjectModel::TYPE_INT;
 			else
 			{
+				// Test if field exists
 				if (!isset($definition['fields'][$fieldname]))
-					throw new PrestashopException('Field '.$fieldname.' not found in class '.$this->classname);
+					throw new PrestaShopException('Field '.$fieldname.' not found in class '.$definition['classname']);
+
+				// Test field validity for language fields
+				if (empty($definition['is_lang']) && !empty($definition['fields'][$fieldname]['lang']))
+					throw new PrestaShopException('Field '.$fieldname.' is declared as lang field but is used in non multilang context');
+				else if (!empty($definition['is_lang']) && empty($definition['fields'][$fieldname]['lang']))
+					throw new PrestaShopException('Field '.$fieldname.' is not declared as lang field but is used in multilang context');
 
 				$type = $definition['fields'][$fieldname]['type'];
 			}
diff --git a/classes/Country.php b/classes/Country.php
index 3607c47a4..6a88bef37 100644
--- a/classes/Country.php
+++ b/classes/Country.php
@@ -86,6 +86,10 @@ class CountryCore extends ObjectModel
 			// Lang fields
 			'name' => 						array('type' => self::TYPE_STRING, 'lang' => true, 'validate' => 'isGenericName', 'required' => true, 'size' => 64),
 		),
+		'associations' => array(
+			'zone' => 						array('type' => self::HAS_ONE),
+			'currency' => 					array('type' => self::HAS_ONE),
+		)
 	);
 
 	protected $webserviceParameters = array(