[ci skip] Fix #5168
diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 9216651..7677f5b 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -1403,11 +1403,9 @@
 		// ORDER BY usage is often problematic here (most notably
 		// on Microsoft SQL Server) and ultimately unnecessary
 		// for selecting COUNT(*) ...
-		if ( ! empty($this->qb_orderby))
-		{
-			$orderby = $this->qb_orderby;
-			$this->qb_orderby = NULL;
-		}
+		$qb_orderby       = $this->qb_order_by;
+		$qb_cache_orderby = $this->qb_cache_orderby;
+		$this->qb_orderby = $this->qb_cache_orderby = NULL;
 
 		$result = ($this->qb_distinct === TRUE OR ! empty($this->qb_groupby) OR ! empty($this->qb_cache_groupby) OR $this->qb_limit OR $this->qb_offset)
 			? $this->query($this->_count_string.$this->protect_identifiers('numrows')."\nFROM (\n".$this->_compile_select()."\n) CI_count_all_results")
@@ -1417,10 +1415,10 @@
 		{
 			$this->_reset_select();
 		}
-		// If we've previously reset the qb_orderby values, get them back
-		elseif ( ! isset($this->qb_orderby))
+		else
 		{
-			$this->qb_orderby = $orderby;
+			$this->qb_orderby       = $qb_orderby;
+			$this->qb_cache_orderby = $qb_cache_orderby;
 		}
 
 		if ($result->num_rows() === 0)
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index fd7485f..77648a9 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -12,6 +12,7 @@
 -------------------
 
 -  Fixed a bug (#5164) - :doc:`Loader Library <libraries/loader>` method ``library()`` ignored requests to load libraries previously assigned to super-object properties named differently than the library name.
+-  Fixed a bug (#5168) - :doc:`Query Builder <database/query_builder>` method ``count_all_results()`` produced erroneous queries on Microsoft SQL Server when ``ORDER BY`` clauses are cached.
 
 Version 3.1.5
 =============