Change DB_result::num_rows default value to NULL
diff --git a/system/database/drivers/odbc/odbc_result.php b/system/database/drivers/odbc/odbc_result.php
index af53211..0085ef6 100644
--- a/system/database/drivers/odbc/odbc_result.php
+++ b/system/database/drivers/odbc/odbc_result.php
@@ -33,11 +33,10 @@
  * @category	Database
  * @author		EllisLab Dev Team
  * @link		http://codeigniter.com/user_guide/database/
+ * @since	1.3
  */
 class CI_DB_odbc_result extends CI_DB_result {
 
-	public $num_rows;
-
 	/**
 	 * Number of rows in the result set
 	 *
@@ -59,6 +58,8 @@
 		return $this->num_rows;
 	}
 
+	// --------------------------------------------------------------------
+
 	/**
 	 * Number of fields in the result set
 	 *