diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadata.php b/lib/Doctrine/ORM/Mapping/ClassMetadata.php
index 059abcd76..38102e475 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadata.php
@@ -384,7 +384,7 @@ final class ClassMetadata
      *
      * @var array
      */
-    //private $_tableGeneratorDefinition;
+    public $tableGeneratorDefinition;
 
     /**
      * The policy used for change-tracking on entities of this class.
diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
index 93ec7fab1..cb17434b8 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
@@ -194,7 +194,7 @@ class ClassMetadataFactory
                     $class->getTableGeneratorDefinition($parent->getTableGeneratorDefinition());
                 }
                 $class->setIdGeneratorType($parent->generatorType);
-                $class->setidGenerator($parent->getIdGenerator());
+                $class->setIdGenerator($parent->getIdGenerator());
             } else {
                 $this->_completeIdGeneratorMapping($class);
             }
diff --git a/lib/Doctrine/ORM/Query/Expr.php b/lib/Doctrine/ORM/Query/Expr.php
index ca94ecb51..08025e69a 100644
--- a/lib/Doctrine/ORM/Query/Expr.php
+++ b/lib/Doctrine/ORM/Query/Expr.php
@@ -73,39 +73,34 @@ class Expr
         return new Expr\GroupBy(func_get_args());
     }
 
-    public static function having($having = null)
-    {
-        return new Expr\Having(func_get_args());
-    }
-
     public static function eq($x, $y)
     {
-        return new Expr\Comparison($x, '=', $y);
+        return new Expr\Comparison($x, Expr\Comparison::EQ, $y);
     }
 
     public static function neq($x, $y)
     {
-        return new Expr\Comparison($x, '<>', $y);
+        return new Expr\Comparison($x, Expr\Comparison::NEQ, $y);
     }
 
     public static function lt($x, $y)
     {
-        return new Expr\Comparison($x, '<', $y);
+        return new Expr\Comparison($x, Expr\Comparison::LT, $y);
     }
 
     public static function lte($x, $y)
     {
-        return new Expr\Comparison($x, '<=', $y);
+        return new Expr\Comparison($x, Expr\Comparison::LTE, $y);
     }
 
     public static function gt($x, $y)
     {
-        return new Expr\Comparison($x, '>', $y);
+        return new Expr\Comparison($x, Expr\Comparison::GT, $y);
     }
 
     public static function gte($x, $y)
     {
-        return new Expr\Comparison($x, '>=', $y);
+        return new Expr\Comparison($x, Expr\Comparison::GTE, $y);
     }
 
     public static function avg($x)
diff --git a/lib/Doctrine/ORM/Query/Expr/Andx.php b/lib/Doctrine/ORM/Query/Expr/Andx.php
index 08f8fbddb..7f8dda84b 100644
--- a/lib/Doctrine/ORM/Query/Expr/Andx.php
+++ b/lib/Doctrine/ORM/Query/Expr/Andx.php
@@ -36,7 +36,7 @@ class Andx extends Base
     protected $_separator = ') AND (';
     protected $_allowedClasses = array(
         'Doctrine\ORM\Query\Expr\Comparison',
+        'Doctrine\ORM\Query\Expr\Func',
         'Doctrine\ORM\Query\Expr\Orx',
-        'Doctrine\ORM\Query\Expr\Func'
     );
 }
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/Query/Expr/Base.php b/lib/Doctrine/ORM/Query/Expr/Base.php
index 7fd563ac0..e96ed6c18 100644
--- a/lib/Doctrine/ORM/Query/Expr/Base.php
+++ b/lib/Doctrine/ORM/Query/Expr/Base.php
@@ -41,6 +41,11 @@ abstract class Base
     private $_parts = array();
 
     public function __construct($args = array())
+    {
+        $this->addMultiple($args);
+    }
+    
+    public function addMultiple($args = array())
     {
         foreach ((array) $args as $arg) {
             $this->add($arg);
@@ -70,6 +75,10 @@ abstract class Base
 
     public function __toString()
     {
+        if ($this->count() == 1) {
+            return (string) $this->_parts[0];
+        }
+        
         return $this->_preSeparator . implode($this->_separator, $this->_parts) . $this->_postSeparator;
     }
 }
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/Query/Expr/Comparison.php b/lib/Doctrine/ORM/Query/Expr/Comparison.php
index 2bc75ae75..2a9b599bf 100644
--- a/lib/Doctrine/ORM/Query/Expr/Comparison.php
+++ b/lib/Doctrine/ORM/Query/Expr/Comparison.php
@@ -32,6 +32,13 @@ namespace Doctrine\ORM\Query\Expr;
  */
 class Comparison
 {
+    const EQ  = '=';
+    const NEQ = '<>';
+    const LT  = '<';
+    const LTE = '<=';
+    const GT  = '>';
+    const GTE = '>=';
+    
     private $_leftExpr;
     private $_operator;
     private $_rightExpr;
diff --git a/lib/Doctrine/ORM/Query/Expr/Having.php b/lib/Doctrine/ORM/Query/Expr/Having.php
index 0eb0f727a..e69de29bb 100644
--- a/lib/Doctrine/ORM/Query/Expr/Having.php
+++ b/lib/Doctrine/ORM/Query/Expr/Having.php
@@ -1,43 +0,0 @@
-<?php
-/*
- *  $Id$
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- * This software consists of voluntary contributions made by many individuals
- * and is licensed under the LGPL. For more information, see
- * <http://www.doctrine-project.org>.
- */
-
-namespace Doctrine\ORM\Query\Expr;
-
-/**
- * Expression class for building DQL Having parts
- *
- * @author      Jonathan H. Wage <jonwage@gmail.com>
- * @author      Guilherme Blanco <guilhermeblanco@gmail.com>
- * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
- * @link        http://www.phpdoctrine.org
- * @since       2.0
- * @version     $Revision$
- */
-class Having extends Base
-{
-    protected $_preSeparator = '';
-    protected $_postSeparator = '';
-    protected $_allowedClasses = array(
-        'Doctrine\ORM\Query\Expr\Comparison',
-        'Doctrine\ORM\Query\Expr\Orx',
-        'Doctrine\ORM\Query\Expr\Func'
-    );
-}
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/Query/Expr/Orx.php b/lib/Doctrine/ORM/Query/Expr/Orx.php
index b4a8ef743..b1aad153c 100644
--- a/lib/Doctrine/ORM/Query/Expr/Orx.php
+++ b/lib/Doctrine/ORM/Query/Expr/Orx.php
@@ -35,8 +35,8 @@ class Orx extends Base
 {
     protected $_separator = ') OR (';
     protected $_allowedClasses = array(
-        'Doctrine\ORM\Query\Expr\Comparison',
         'Doctrine\ORM\Query\Expr\Andx',
-        'Doctrine\ORM\Query\Expr\Func'
+        'Doctrine\ORM\Query\Expr\Comparison',
+        'Doctrine\ORM\Query\Expr\Func',
     );
 }
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/QueryBuilder.php b/lib/Doctrine/ORM/QueryBuilder.php
index b7520cc0e..ee874b475 100644
--- a/lib/Doctrine/ORM/QueryBuilder.php
+++ b/lib/Doctrine/ORM/QueryBuilder.php
@@ -55,11 +55,13 @@ class QueryBuilder
      * @var array $dqlParts The array of DQL parts collected.
      */
     private $_dqlParts = array(
-        'select' => array(),
-        'from' => array(),
-        'where' => array(),
+        'select'  => array(),
+        'from'    => null,
+        'join'    => array(),
+        'set'     => array(),
+        'where'   => null,
         'groupBy' => array(),
-        'having' => array(),
+        'having'  => null,
         'orderBy' => array()
     );
 
@@ -201,10 +203,12 @@ class QueryBuilder
      */
     public function add($dqlPartName, $dqlPart, $append = false)
     {
-        if ($append) {
+        $isMultiple = is_array($this->_dqlParts[$dqlPartName]);
+    
+        if ($append && $isMultiple) {
             $this->_dqlParts[$dqlPartName][] = $dqlPart;
         } else {
-            $this->_dqlParts[$dqlPartName] = array($dqlPart);
+            $this->_dqlParts[$dqlPartName] = ($isMultiple) ? array($dqlPart) : $dqlPart;
         }
 
         $this->_state = self::STATE_DIRTY;
@@ -214,15 +218,14 @@ class QueryBuilder
 
     public function select($select = null)
     {
-        $selects = func_get_args();
         $this->_type = self::SELECT;
+        $selects = func_get_args();
 
         if (empty($selects)) {
             return $this;
         }
-
-        $select = call_user_func_array(array('Doctrine\ORM\Query\Expr', 'select'), $selects);
-        return $this->add('select', $select, true);
+        
+        return $this->add('select', new Expr\Select($selects), true);
     }
 
     public function delete($delete = null, $alias = null)
@@ -233,7 +236,7 @@ class QueryBuilder
             return $this;
         }
 
-        return $this->add('from', Expr::from($delete, $alias));
+        return $this->add('from', new Expr\From($delete, $alias));
     }
 
     public function update($update = null, $alias = null)
@@ -244,89 +247,90 @@ class QueryBuilder
             return $this;
         }
 
-        return $this->add('from', Expr::from($update, $alias));
-    }
-
-    public function set($key, $value)
-    {
-        return $this->add('set', Expr::eq($key, $value), true);
+        return $this->add('from', new Expr\From($update, $alias));
     }
 
     public function from($from, $alias = null)
     {
-        return $this->add('from', Expr::from($from, $alias), true);
+        return $this->add('from', new Expr\From($from, $alias));
     }
     
     public function innerJoin($join, $alias = null, $conditionType = null, $condition = null)
     {
-        return $this->add('from', Expr::innerJoin($join, $alias, $conditionType, $condition), true);
+        return $this->add('join', new Expr\Join(
+            Expr\Join::INNER_JOIN, $join, $alias, $conditionType, $condition
+        ), true);
     }
 
     public function leftJoin($join, $alias = null, $conditionType = null, $condition = null)
     {
-        return $this->add('from', Expr::leftJoin($join, $alias, $conditionType, $condition), true);
+        return $this->add('join', new Expr\Join(
+            Expr\Join::LEFT_JOIN, $join, $alias, $conditionType, $condition
+        ), true);
+    }
+
+    public function set($key, $value)
+    {
+        return $this->add('set', new Expr\Comparison($key, Expr\Comparison::EQ, $value), true);
     }
 
     public function where($where)
     {
-        $where = call_user_func_array(array('Doctrine\ORM\Query\Expr', 'andx'), func_get_args());
-        return $this->add('where', $where, false);
+        if ( ! (func_num_args() == 1 && ($where instanceof Expr\Andx || $where instanceof Expr\Orx))) {
+            $where = new Expr\Andx(func_get_args());
+        }
+        
+        return $this->add('where', $where);
     }
 
     public function andWhere($where)
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'AND', true);
+        $where = $this->_getDqlQueryPart('where');
+        $args = func_get_args();
+        
+        if ($where instanceof Expr\Andx) {
+            $where->addMultiple($args);
+        } else { 
+            array_unshift($args, $where);
+            $where = new Expr\Andx($args);
         }
-
-        $where = call_user_func_array(array('Doctrine\ORM\Query\Expr', 'andx'), func_get_args());
-        return $this->add('where', $where, true);
+        
+        return $this->add('where', $where);
     }
 
     public function orWhere($where)
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'OR', true);
+        $where = $this->_getDqlQueryPart('where');
+        $args = func_get_args();
+        
+        if ($where instanceof Expr\Orx) {
+            $where->addMultiple($args);
+        } else {            
+            array_unshift($args, $where);
+            $where = new Expr\Orx($args);
         }
-
-        $where = call_user_func_array(array('Doctrine\ORM\Query\Expr', 'orx'), func_get_args());
-        return $this->add('where', $where, true);
+        
+        return $this->add('where', $where);
     }
 
     public function andWhereIn($expr, $params)
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'AND', true);
-        }
-
-        return $this->add('where', Expr::in($expr, $params), true);
+        return $this->andWhere(Expr::in($expr, $params));
     }
 
     public function orWhereIn($expr, $params = array())
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'OR', true);
-        }
-
-        return $this->add('where', Expr::in($expr, $params), true);
+        return $this->orWhere(Expr::in($expr, $params));
     }
 
     public function andWhereNotIn($expr, $params = array())
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'AND', true);
-        }
-
-        return $this->add('where', Expr::notIn($expr, $params), true);
+        return $this->andWhere(Expr::notIn($expr, $params));
     }
 
     public function orWhereNotIn($expr, $params = array())
     {
-        if (count($this->_getDqlQueryPart('where')) > 0) {
-            $this->add('where', 'OR', true);
-        }
-
-        return $this->add('where', Expr::notIn($expr, $params), true);
+        return $this->orWhere(Expr::notIn($expr, $params));
     }
 
     public function groupBy($groupBy)
@@ -341,25 +345,41 @@ class QueryBuilder
 
     public function having($having)
     {
-        return $this->add('having', Expr::having($having), false);
+        if ( ! (func_num_args() == 1 && ($having instanceof Expr\Andx || $having instanceof Expr\Orx))) {
+            $having = new Expr\Andx(func_get_args());
+        }
+        
+        return $this->add('having', $having);
     }
 
     public function andHaving($having)
     {
-        if (count($this->_getDqlQueryPart('having')) > 0) {
-            $this->add('having', 'AND', true);
+        $having = $this->_getDqlQueryPart('having');
+        $args = func_get_args();
+        
+        if ($having instanceof Expr\Andx) {
+            $having->addMultiple($args);
+        } else { 
+            array_unshift($args, $having);
+            $having = new Expr\Andx($args);
         }
-
-        return $this->add('having', Expr::having($having), true);
+        
+        return $this->add('having', $having);
     }
 
     public function orHaving($having)
     {
-        if (count($this->_getDqlQueryPart('having')) > 0) {
-            $this->add('having', 'OR', true);
+        $having = $this->_getDqlQueryPart('having');
+        $args = func_get_args();
+        
+        if ($having instanceof Expr\Orx) {
+            $having->addMultiple($args);
+        } else { 
+            array_unshift($args, $having);
+            $having = new Expr\Orx($args);
         }
-
-        return $this->add('having', Expr::having($having), true);
+        
+        return $this->add('having', $having);
     }
 
     public function orderBy($sort, $order = null)
@@ -374,8 +394,7 @@ class QueryBuilder
 
     /**
      * Get the DQL query string for DELETE queries
-     *
-     * BNF:
+     * EBNF:
      *
      * DeleteStatement = DeleteClause [WhereClause] [OrderByClause] [LimitClause] [OffsetClause]
      * DeleteClause    = "DELETE" "FROM" RangeVariableDeclaration
@@ -389,15 +408,14 @@ class QueryBuilder
     private function _getDqlForDelete()
     {
          return 'DELETE'
-              . $this->_getReducedDqlQueryPart('from', array('pre' => ' ', 'separator' => ' '))
-              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('from', array('pre' => ' '))
+              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE '))
               . $this->_getReducedDqlQueryPart('orderBy', array('pre' => ' ORDER BY ', 'separator' => ', '));
     }
 
     /**
      * Get the DQL query string for UPDATE queries
-     *
-     * BNF:
+     * EBNF:
      *
      * UpdateStatement = UpdateClause [WhereClause] [OrderByClause]
      * UpdateClause    = "UPDATE" RangeVariableDeclaration "SET" UpdateItem {"," UpdateItem}
@@ -409,16 +427,15 @@ class QueryBuilder
     private function _getDqlForUpdate()
     {
          return 'UPDATE'
-              . $this->_getReducedDqlQueryPart('from', array('pre' => ' ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('from', array('pre' => ' '))
               . $this->_getReducedDqlQueryPart('set', array('pre' => ' SET ', 'separator' => ', '))
-              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE '))
               . $this->_getReducedDqlQueryPart('orderBy', array('pre' => ' ORDER BY ', 'separator' => ', '));
     }
 
     /**
      * Get the DQL query string for SELECT queries
-     *
-     * BNF:
+     * EBNF:
      *
      * SelectStatement = [SelectClause] FromClause [WhereClause] [GroupByClause] [HavingClause] [OrderByClause]
      * SelectClause    = "SELECT" ["ALL" | "DISTINCT"] SelectExpression {"," SelectExpression}
@@ -432,26 +449,27 @@ class QueryBuilder
      */
     private function _getDqlForSelect()
     {
-         return 'SELECT'
+         return 'SELECT' 
               . $this->_getReducedDqlQueryPart('select', array('pre' => ' ', 'separator' => ', '))
-              . $this->_getReducedDqlQueryPart('from', array('pre' => ' FROM ', 'separator' => ' '))
-              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('from', array('pre' => ' FROM '))
+              . $this->_getReducedDqlQueryPart('join', array('pre' => ' ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('where', array('pre' => ' WHERE '))
               . $this->_getReducedDqlQueryPart('groupBy', array('pre' => ' GROUP BY ', 'separator' => ', '))
-              . $this->_getReducedDqlQueryPart('having', array('pre' => ' HAVING ', 'separator' => ' '))
+              . $this->_getReducedDqlQueryPart('having', array('pre' => ' HAVING '))
               . $this->_getReducedDqlQueryPart('orderBy', array('pre' => ' ORDER BY ', 'separator' => ', '));
     }
 
     private function _getReducedDqlQueryPart($queryPartName, $options = array())
     {
-        if (empty($this->_dqlParts[$queryPartName])) {
+        $queryPart = $this->_getDqlQueryPart($queryPartName);
+        
+        if (empty($queryPart)) {
             return (isset($options['empty']) ? $options['empty'] : '');
         }
-
-        $str  = (isset($options['pre']) ? $options['pre'] : '');
-        $str .= implode($options['separator'], $this->_getDqlQueryPart($queryPartName));
-        $str .= (isset($options['post']) ? $options['post'] : '');
-
-        return $str;
+        
+        return (isset($options['pre']) ? $options['pre'] : '')
+             . (is_array($queryPart) ? implode($options['separator'], $queryPart) : $queryPart)
+             . (isset($options['post']) ? $options['post'] : '');
     }
 
     private function _getDqlQueryPart($queryPartName)
diff --git a/lib/Doctrine/ORM/Tools/SchemaTool.php b/lib/Doctrine/ORM/Tools/SchemaTool.php
index 4dc17ff5c..d6554554a 100644
--- a/lib/Doctrine/ORM/Tools/SchemaTool.php
+++ b/lib/Doctrine/ORM/Tools/SchemaTool.php
@@ -150,6 +150,8 @@ class SchemaTool
                     $class->getQuotedTableName($this->_platform), $columns, $options));
             $processedClasses[$class->name] = true;
 
+            // TODO if we're reusing the sequence previously defined (in another model),
+            // it should not attempt to create a new sequence.
             if ($class->isIdGeneratorSequence() && $class->name == $class->rootEntityName) {
                 $seqDef = $class->getSequenceGeneratorDefinition();
                 $sequences[] = $this->_platform->getCreateSequenceSql(
diff --git a/tests/Doctrine/Tests/ORM/Query/ExprTest.php b/tests/Doctrine/Tests/ORM/Query/ExprTest.php
index 41acb1cbe..b2f0f09ab 100644
--- a/tests/Doctrine/Tests/ORM/Query/ExprTest.php
+++ b/tests/Doctrine/Tests/ORM/Query/ExprTest.php
@@ -75,7 +75,7 @@ class ExprTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder();
         $qb->select('u')->from('User', 'u')->where('u.name = ?1');
         
-        $this->assertEquals('EXISTS(SELECT u FROM User u WHERE (u.name = ?1))', (string) Expr::exists($qb));
+        $this->assertEquals('EXISTS(SELECT u FROM User u WHERE u.name = ?1)', (string) Expr::exists($qb));
     }
 
     public function testAllExpr()
@@ -83,7 +83,7 @@ class ExprTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder();
         $qb->select('u')->from('User', 'u')->where('u.name = ?1');
     
-        $this->assertEquals('ALL(SELECT u FROM User u WHERE (u.name = ?1))', (string) Expr::all($qb));
+        $this->assertEquals('ALL(SELECT u FROM User u WHERE u.name = ?1)', (string) Expr::all($qb));
     }
 
     public function testSomeExpr()
@@ -91,7 +91,7 @@ class ExprTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder();
         $qb->select('u')->from('User', 'u')->where('u.name = ?1');
     
-        $this->assertEquals('SOME(SELECT u FROM User u WHERE (u.name = ?1))', (string) Expr::some($qb));
+        $this->assertEquals('SOME(SELECT u FROM User u WHERE u.name = ?1)', (string) Expr::some($qb));
     }
 
     public function testAnyExpr()
@@ -99,7 +99,7 @@ class ExprTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder();
         $qb->select('u')->from('User', 'u')->where('u.name = ?1');
     
-        $this->assertEquals('ANY(SELECT u FROM User u WHERE (u.name = ?1))', (string) Expr::any($qb));
+        $this->assertEquals('ANY(SELECT u FROM User u WHERE u.name = ?1)', (string) Expr::any($qb));
     }
 
     public function testNotExpr()
@@ -107,13 +107,21 @@ class ExprTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder();
         $qb->select('u')->from('User', 'u')->where('u.name = ?1');
     
-        $this->assertEquals('NOT(SELECT u FROM User u WHERE (u.name = ?1))', (string) Expr::not($qb));
+        $this->assertEquals('NOT(SELECT u FROM User u WHERE u.name = ?1)', (string) Expr::not($qb));
     }
 
     public function testAndExpr()
     {
         $this->assertEquals('(1 = 1) AND (2 = 2)', (string) Expr::andx((string) Expr::eq(1, 1), (string) Expr::eq(2, 2)));
     }
+    
+    public function testIntelligentParenthesisPreventionAndExpr()
+    {
+        $this->assertEquals(
+            '(1 = 1) AND (2 = 2)', 
+            (string) Expr::andx(Expr::orx(Expr::andx(Expr::eq(1, 1))), (string) Expr::eq(2, 2))
+        );
+    }
 
     public function testOrExpr()
     {
diff --git a/tests/Doctrine/Tests/ORM/QueryBuilderTest.php b/tests/Doctrine/Tests/ORM/QueryBuilderTest.php
index 54cef6f86..d5e6e28e9 100644
--- a/tests/Doctrine/Tests/ORM/QueryBuilderTest.php
+++ b/tests/Doctrine/Tests/ORM/QueryBuilderTest.php
@@ -156,7 +156,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->from('Doctrine\Tests\Models\CMS\CmsUser', 'u')
             ->where('u.id = :uid');
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid)');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE u.id = :uid');
     }
 
     public function testAndWhere()
@@ -189,7 +189,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->where('u.id = :uid')
             ->andWhereIn('u.id', array(1, 2, 3));
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) AND u.id IN(1, 2, 3)');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) AND (u.id IN(1, 2, 3))');
     }
 
     public function testOrWhereIn()
@@ -200,7 +200,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->where('u.id = :uid')
             ->orWhereIn('u.id', array(1, 2, 3));
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) OR u.id IN(1, 2, 3)');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) OR (u.id IN(1, 2, 3))');
     }
 
     public function testAndWhereNotIn()
@@ -211,7 +211,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->where('u.id = :uid')
             ->andWhereNotIn('u.id', array(1, 2, 3));
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) AND u.id NOT IN(1, 2, 3)');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) AND (u.id NOT IN(1, 2, 3))');
     }
 
     public function testOrWhereNotIn()
@@ -222,7 +222,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->where('u.id = :uid')
             ->OrWhereNotIn('u.id', array(1, 2, 3));
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) OR u.id NOT IN(1, 2, 3)');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid) OR (u.id NOT IN(1, 2, 3))');
     }
 
     public function testGroupBy()
@@ -256,7 +256,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->having('COUNT(u.id) > 1')
             ->andHaving('COUNT(u.id) < 1');
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u GROUP BY u.id HAVING COUNT(u.id) > 1 AND COUNT(u.id) < 1');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u GROUP BY u.id HAVING (COUNT(u.id) > 1) AND (COUNT(u.id) < 1)');
     }
 
     public function testOrHaving()
@@ -269,7 +269,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->andHaving('COUNT(u.id) < 1')
             ->orHaving('COUNT(u.id) > 1');
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u GROUP BY u.id HAVING COUNT(u.id) > 1 AND COUNT(u.id) < 1 OR COUNT(u.id) > 1');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u GROUP BY u.id HAVING ((COUNT(u.id) > 1) AND (COUNT(u.id) < 1)) OR (COUNT(u.id) > 1)');
     }
 
     public function testOrderBy()
@@ -319,7 +319,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
         $qb = $this->_em->createQueryBuilder()
             ->select('u')
             ->from('Doctrine\Tests\Models\CMS\CmsUser', 'u')
-            ->where('u.username = :username OR u.username = :username2');
+            ->where(Expr::orx('u.username = :username', 'u.username = :username2'));
 
         $qb->setParameters(array('username' => 'jwage', 'username2' => 'jonwage'));
 
@@ -390,7 +390,7 @@ class QueryBuilderTest extends \Doctrine\Tests\OrmTestCase
             ->from('Doctrine\Tests\Models\CMS\CmsUser', 'u')
             ->where($orExpr);
 
-        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE ((u.id = :uid3) OR (u.id IN(1)))');
+        $this->assertValidQueryBuilder($qb, 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE (u.id = :uid3) OR (u.id IN(1))');
     }
 
     public function testGetEntityManager()