diff --git a/app/code/core/Mage/Adminhtml/Helper/Help/Mapping.php b/app/code/core/Mage/Adminhtml/Helper/Help/Mapping.php
index e8727e2b36f..08e74660fd0 100644
--- a/app/code/core/Mage/Adminhtml/Helper/Help/Mapping.php
+++ b/app/code/core/Mage/Adminhtml/Helper/Help/Mapping.php
@@ -231,7 +231,7 @@ protected function findInMapping($frontModule, $controllerName, $actionName)
     /**
      * Determine which version of docs should target onto
      *
-     * @return string
+     * @return false|Varien_Simplexml_Element
      */
     protected function getHelpTargetVersion()
     {
diff --git a/app/code/core/Mage/CatalogSearch/Model/Resource/Search/Collection.php b/app/code/core/Mage/CatalogSearch/Model/Resource/Search/Collection.php
index 7862c441895..c492cb21fcb 100644
--- a/app/code/core/Mage/CatalogSearch/Model/Resource/Search/Collection.php
+++ b/app/code/core/Mage/CatalogSearch/Model/Resource/Search/Collection.php
@@ -105,7 +105,7 @@ protected function _hasAttributeOptionsAndSearchable($attribute)
      * Retrieve SQL for search entities
      *
      * @param string $query
-     * @return string
+     * @return Varien_Db_Select
      */
     protected function _getSearchEntityIdsSql($query)
     {
@@ -168,7 +168,7 @@ protected function _getSearchEntityIdsSql($query)
      * Retrieve SQL for search entities by option
      *
      * @param string $query
-     * @return false|string
+     * @return false|Varien_Db_Select
      */
     protected function _getSearchInOptionSql($query)
     {
diff --git a/app/code/core/Mage/Core/Model/Session/Abstract.php b/app/code/core/Mage/Core/Model/Session/Abstract.php
index c3b858d04c3..b6d55432502 100644
--- a/app/code/core/Mage/Core/Model/Session/Abstract.php
+++ b/app/code/core/Mage/Core/Model/Session/Abstract.php
@@ -524,7 +524,7 @@ public function getSessionHosts()
     /**
      * Retrieve session save method
      *
-     * @return string
+     * @return string|Varien_Simplexml_Element
      */
     public function getSessionSaveMethod()
     {
@@ -537,7 +537,7 @@ public function getSessionSaveMethod()
     /**
      * Get session save path
      *
-     * @return string
+     * @return string|Varien_Simplexml_Element
      */
     public function getSessionSavePath()
     {
diff --git a/app/code/core/Mage/Newsletter/Model/Resource/Subscriber/Collection.php b/app/code/core/Mage/Newsletter/Model/Resource/Subscriber/Collection.php
index 05de12c54c9..babcd29416a 100644
--- a/app/code/core/Mage/Newsletter/Model/Resource/Subscriber/Collection.php
+++ b/app/code/core/Mage/Newsletter/Model/Resource/Subscriber/Collection.php
@@ -173,7 +173,7 @@ public function showStoreInfo()
      * @deprecated after 1.4.0.0-rc1
      *
      * @param string $field
-     * @return string
+     * @return string|Zend_Db_Expr
      */
     public function _getFieldTableAlias($field)
     {
diff --git a/app/code/core/Mage/Sales/Model/Resource/Report/Invoiced/Collection/Order.php b/app/code/core/Mage/Sales/Model/Resource/Report/Invoiced/Collection/Order.php
index ee7b289e758..9f9e8662e5a 100644
--- a/app/code/core/Mage/Sales/Model/Resource/Report/Invoiced/Collection/Order.php
+++ b/app/code/core/Mage/Sales/Model/Resource/Report/Invoiced/Collection/Order.php
@@ -24,7 +24,7 @@ class Mage_Sales_Model_Resource_Report_Invoiced_Collection_Order extends Mage_Sa
     /**
      * Period format
      *
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/app/code/core/Mage/Sales/Model/Resource/Report/Order/Collection.php b/app/code/core/Mage/Sales/Model/Resource/Report/Order/Collection.php
index 4e49fec48cc..6810a3b9029 100644
--- a/app/code/core/Mage/Sales/Model/Resource/Report/Order/Collection.php
+++ b/app/code/core/Mage/Sales/Model/Resource/Report/Order/Collection.php
@@ -24,7 +24,7 @@ class Mage_Sales_Model_Resource_Report_Order_Collection extends Mage_Sales_Model
     /**
      * Period format
      *
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/app/code/core/Mage/Sales/Model/Resource/Report/Refunded/Collection/Order.php b/app/code/core/Mage/Sales/Model/Resource/Report/Refunded/Collection/Order.php
index 0e568ccf98b..1872af34d95 100644
--- a/app/code/core/Mage/Sales/Model/Resource/Report/Refunded/Collection/Order.php
+++ b/app/code/core/Mage/Sales/Model/Resource/Report/Refunded/Collection/Order.php
@@ -24,7 +24,7 @@ class Mage_Sales_Model_Resource_Report_Refunded_Collection_Order extends Mage_Sa
     /**
      * Period format
      *
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/app/code/core/Mage/Sales/Model/Resource/Report/Shipping/Collection/Order.php b/app/code/core/Mage/Sales/Model/Resource/Report/Shipping/Collection/Order.php
index 6f4108d7275..3054e6597b8 100644
--- a/app/code/core/Mage/Sales/Model/Resource/Report/Shipping/Collection/Order.php
+++ b/app/code/core/Mage/Sales/Model/Resource/Report/Shipping/Collection/Order.php
@@ -24,7 +24,7 @@ class Mage_Sales_Model_Resource_Report_Shipping_Collection_Order extends Mage_Sa
     /**
      * Period format
      *
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/app/code/core/Mage/SalesRule/Model/Resource/Report/Collection.php b/app/code/core/Mage/SalesRule/Model/Resource/Report/Collection.php
index 354e7162f6b..93ed63c9c28 100644
--- a/app/code/core/Mage/SalesRule/Model/Resource/Report/Collection.php
+++ b/app/code/core/Mage/SalesRule/Model/Resource/Report/Collection.php
@@ -24,7 +24,7 @@ class Mage_SalesRule_Model_Resource_Report_Collection extends Mage_Sales_Model_R
     /**
      * Period format for report (day, month, year)
      *
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/app/code/core/Mage/Tax/Model/Resource/Report/Collection.php b/app/code/core/Mage/Tax/Model/Resource/Report/Collection.php
index 83364b3ca50..291994d8c6a 100644
--- a/app/code/core/Mage/Tax/Model/Resource/Report/Collection.php
+++ b/app/code/core/Mage/Tax/Model/Resource/Report/Collection.php
@@ -22,7 +22,7 @@
 class Mage_Tax_Model_Resource_Report_Collection extends Mage_Sales_Model_Resource_Report_Collection_Abstract
 {
     /**
-     * @var string
+     * @var Zend_Db_Expr
      */
     protected $_periodFormat;
 
diff --git a/lib/Varien/Db/Adapter/Pdo/Mysql.php b/lib/Varien/Db/Adapter/Pdo/Mysql.php
index 93412dad7c6..7a47afc1562 100644
--- a/lib/Varien/Db/Adapter/Pdo/Mysql.php
+++ b/lib/Varien/Db/Adapter/Pdo/Mysql.php
@@ -277,7 +277,7 @@ public function getTransactionLevel()
      * Convert date to DB format
      *
      * @param   int|string|Zend_Date $date
-     * @return  string
+     * @return  Zend_Db_Expr
      */
     public function convertDate($date)
     {
@@ -288,11 +288,11 @@ public function convertDate($date)
      * Convert date and time to DB format
      *
      * @param   int|string|Zend_Date $datetime
-     * @return  string
+     * @return  Zend_Db_Expr
      */
     public function convertDateTime($datetime)
     {
-        return $this->formatDate($datetime, true);
+        return $this->formatDate($datetime);
     }
 
     /**