diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
index a021f756c..2044932d6 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
@@ -340,7 +340,7 @@ class ClassMetadataFactory implements ClassMetadataFactoryInterface
     {
         // Verify & complete identifier mapping
         if ( ! $class->identifier && ! $class->isMappedSuperclass) {
-            throw MappingException::identifierRequired($className);
+            throw MappingException::identifierRequired($class->name);
         }
 
         // verify inheritance
diff --git a/lib/Doctrine/ORM/Query/SqlWalker.php b/lib/Doctrine/ORM/Query/SqlWalker.php
index 2a9f58faf..7393ba893 100644
--- a/lib/Doctrine/ORM/Query/SqlWalker.php
+++ b/lib/Doctrine/ORM/Query/SqlWalker.php
@@ -359,13 +359,7 @@ class SqlWalker implements TreeWalker
     {
         $sql = $this->walkSelectClause($AST->selectClause);
         $sql .= $this->walkFromClause($AST->fromClause);
-
-        if (($whereClause = $AST->whereClause) !== null) {
-            $sql .= $this->walkWhereClause($whereClause);
-        } else if (($discSql = $this->_generateDiscriminatorColumnConditionSQL($this->_rootAliases)) !== '') {
-            $sql .= ' WHERE ' . $discSql;
-        }
-
+        $sql .= $this->walkWhereClause($AST->whereClause);
         $sql .= $AST->groupByClause ? $this->walkGroupByClause($AST->groupByClause) : '';
         $sql .= $AST->havingClause ? $this->walkHavingClause($AST->havingClause) : '';
 
@@ -407,12 +401,7 @@ class SqlWalker implements TreeWalker
     {
         $this->_useSqlTableAliases = false;
         $sql = $this->walkUpdateClause($AST->updateClause);
-
-        if (($whereClause = $AST->whereClause) !== null) {
-            $sql .= $this->walkWhereClause($whereClause);
-        } else if (($discSql = $this->_generateDiscriminatorColumnConditionSQL($this->_rootAliases)) !== '') {
-            $sql .= ' WHERE ' . $discSql;
-        }
+        $sql .= $this->walkWhereClause($AST->whereClause);
 
         return $sql;
     }
@@ -427,12 +416,7 @@ class SqlWalker implements TreeWalker
     {
         $this->_useSqlTableAliases = false;
         $sql = $this->walkDeleteClause($AST->deleteClause);
-
-        if (($whereClause = $AST->whereClause) !== null) {
-            $sql .= $this->walkWhereClause($whereClause);
-        } else if (($discSql = $this->_generateDiscriminatorColumnConditionSQL($this->_rootAliases)) !== '') {
-            $sql .= ' WHERE ' . $discSql;
-        }
+        $sql .= $this->walkWhereClause($AST->whereClause);
 
         return $sql;
     }
@@ -1158,15 +1142,19 @@ class SqlWalker implements TreeWalker
     public function walkSubselect($subselect)
     {
         $useAliasesBefore = $this->_useSqlTableAliases;
+        $rootAliasesBefore = $this->_rootAliases;
+
+        $this->_rootAliases = array(); // reset the rootAliases for the subselect
         $this->_useSqlTableAliases = true;
 
         $sql = $this->walkSimpleSelectClause($subselect->simpleSelectClause);
         $sql .= $this->walkSubselectFromClause($subselect->subselectFromClause);
-        $sql .= $subselect->whereClause ? $this->walkWhereClause($subselect->whereClause) : '';
+        $sql .= $this->walkWhereClause($subselect->whereClause);
         $sql .= $subselect->groupByClause ? $this->walkGroupByClause($subselect->groupByClause) : '';
         $sql .= $subselect->havingClause ? $this->walkHavingClause($subselect->havingClause) : '';
         $sql .= $subselect->orderByClause ? $this->walkOrderByClause($subselect->orderByClause) : '';
 
+        $this->_rootAliases = $rootAliasesBefore; // put the main aliases back
         $this->_useSqlTableAliases = $useAliasesBefore;
 
         return $sql;
@@ -1193,6 +1181,8 @@ class SqlWalker implements TreeWalker
             $sql .= $class->getQuotedTableName($this->_platform) . ' '
                   . $this->getSQLTableAlias($class->table['name'], $dqlAlias);
 
+            $this->_rootAliases[] = $dqlAlias;
+
             if ($class->isInheritanceTypeJoined()) {
                 $sql .= $this->_generateClassTableInheritanceJoins($class, $dqlAlias);
             }
@@ -1414,16 +1404,23 @@ class SqlWalker implements TreeWalker
 
     /**
      * Walks down a WhereClause AST node, thereby generating the appropriate SQL.
+     * WhereClause or not, the appropriate discriminator sql is added.
      *
      * @param WhereClause
      * @return string The SQL.
      */
     public function walkWhereClause($whereClause)
     {
+        $condSql = null !== $whereClause ? $this->walkConditionalExpression($whereClause->conditionalExpression) : '';
         $discrSql = $this->_generateDiscriminatorColumnConditionSql($this->_rootAliases);
-        $condSql = $this->walkConditionalExpression($whereClause->conditionalExpression);
 
-        return ' WHERE ' . (( ! $discrSql) ? $condSql : '(' . $condSql . ') AND ' . $discrSql);
+        if ($condSql) {
+            return ' WHERE ' . (( ! $discrSql) ? $condSql : '(' . $condSql . ') AND ' . $discrSql);
+        } else if ($discrSql) {
+            return ' WHERE ' . $discrSql;
+        }
+
+        return '';
     }
 
     /**
diff --git a/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php b/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
index deffb9232..ad5ce1329 100644
--- a/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
+++ b/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
@@ -922,6 +922,49 @@ class SelectSqlGenerationTest extends \Doctrine\Tests\OrmTestCase
             "SELECT COALESCE(NULLIF(c0_.name, ''), c0_.username) AS sclr0 FROM cms_users c0_"
         );
     }
+
+    /**
+     * Test that the right discriminator data is inserted in a subquery.
+     */
+    public function testSubSelectDiscriminator()
+    {
+        $this->assertSqlGeneration(
+            "SELECT u.name, (SELECT COUNT(cfc.id) total FROM Doctrine\Tests\Models\Company\CompanyFixContract cfc) as cfc_count FROM Doctrine\Tests\Models\CMS\CmsUser u",
+            "SELECT c0_.name AS name0, (SELECT COUNT(c1_.id) AS dctrn__total FROM company_contracts c1_ WHERE c1_.discr IN ('fix')) AS sclr1 FROM cms_users c0_"
+        );
+    }
+
+    public function testIdVariableResultVariableReuse()
+    {
+        $exceptionThrown = false;
+        try {
+            $query = $this->_em->createQuery("SELECT u.name FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE u.name IN (SELECT u.name FROM Doctrine\Tests\Models\CMS\CmsUser u)");
+
+            $query->getSql();
+            $query->free();
+        } catch (\Exception $e) {
+            $exceptionThrown = true;
+        }
+
+        $this->assertTrue($exceptionThrown);
+
+    }
+
+    public function testSubSelectAliasesFromOuterQuery()
+    {
+        $this->assertSqlGeneration(
+            "SELECT uo, (SELECT ui.name FROM Doctrine\Tests\Models\CMS\CmsUser ui WHERE ui.id = uo.id) AS bar FROM Doctrine\Tests\Models\CMS\CmsUser uo",
+            "SELECT c0_.id AS id0, c0_.status AS status1, c0_.username AS username2, c0_.name AS name3, (SELECT c1_.name FROM cms_users c1_ WHERE c1_.id = c0_.id) AS sclr4 FROM cms_users c0_"
+        );
+    }
+
+    public function testSubSelectAliasesFromOuterQueryWithSubquery()
+    {
+        $this->assertSqlGeneration(
+            "SELECT uo, (SELECT ui.name FROM Doctrine\Tests\Models\CMS\CmsUser ui WHERE ui.id = uo.id AND ui.name IN (SELECT uii.name FROM Doctrine\Tests\Models\CMS\CmsUser uii)) AS bar FROM Doctrine\Tests\Models\CMS\CmsUser uo",
+            "SELECT c0_.id AS id0, c0_.status AS status1, c0_.username AS username2, c0_.name AS name3, (SELECT c1_.name FROM cms_users c1_ WHERE c1_.id = c0_.id AND c1_.name IN (SELECT c2_.name FROM cms_users c2_)) AS sclr4 FROM cms_users c0_"
+        );
+    }
 }