---
title: "Changes to behavior of string-length and substring | Microsoft Docs"
ms.custom: ""
ms.date: "06/13/2017"
ms.prod: "sql-server-2014"
ms.reviewer: ""
ms.technology: "database-engine"
ms.topic: conceptual
ms.assetid: 2119b7ba-2e52-44bf-ac57-82c2d46a48ff
author: mashamsft
ms.author: mathoma
manager: craigg
---
# Changes to behavior of string-length and substring
  The [string-length Function (XQuery)](/sql/xquery/functions-on-string-values-string-length) and [substring Function (XQuery)](/sql/xquery/functions-on-string-values-substring) functions may return different results when used with XML databases that contain surrogate characters.  
  
## Description  
 When a database is set to be compatible with [!INCLUDE[ssSQL11](../../includes/sssql11-md.md)], the behavior of the [string-length Function (XQuery)](/sql/xquery/functions-on-string-values-string-length) and [substring Function (XQuery)](/sql/xquery/functions-on-string-values-substring) functions changes when dealing with Unicode supplementary characters. Each Unicode supplementary character, which is defined by having a code point larger than U+FFFF, is counted as one character by these functions rather than two, as it was in previous versions.  
  
 For more information about surrogate characters, see [Surrogates and Supplementary Characters](https://go.microsoft.com/fwlink/?LinkId=178317).  
  
## See Also  
 [Database Engine Upgrade Issues](../../../2014/sql-server/install/database-engine-upgrade-issues.md)   
 [SQL Server 2014 Upgrade Advisor [new]](https://docs.microsoft.com/sql/sql-server/install/sql-server-2014-upgrade-advisor)