基于字符串值的函数 - lower-case
适用范围：
SQL Server
小写函数将$arg中的每个字符转换为其小写等效字符。 Unicode 码位的 Microsoft Windows 二进制大小写转换指定如何将字符转换为小写。 这一标准与 Unicode 码位标准的映射不相同。
语法
fn:lower-case($arg as xs:string?) as xs:string
参数
| 术语 | 定义 |
|---|---|
| $arg | 要转换为小写的字符串值。 |
注解
如果$arg的值为空，则返回零长度字符串。
示例
A. 将字符串更改为小写
以下示例将输入字符串“abcDEF！@4”更改为小写。
DECLARE @x xml = N'abcDEF!@4';
SELECT @x.value('fn:lower-case(/text()[1])', 'nvarchar(10)');
结果集如下。
abcdef!@4
B. 搜索特定字符串
本示例说明如何使用 lower-case 函数执行不区分大小写的搜索。
USE AdventureWorks2022;
GO
--WITH XMLNAMESPACES clause specifies the namespace prefix
--to use.
WITH XMLNAMESPACES ('https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription' AS pd)
--The XQuery contains() function is used to determine whether
--any of the text nodes below the <Summary> element contain
--the word 'frame'. The lower-case() function makes the
--case insensitive.
SELECT ProductModelID, CatalogDescription.query('
<Prod>
{ /pd:ProductDescription/@ProductModelID }
{ /pd:ProductDescription/pd:Summary }
</Prod>
') as Result
FROM Production.ProductModel
where CatalogDescription.exist('
/pd:ProductDescription/pd:Summary//text()[
contains(lower-case(.), "FRAME")]') = 1
结果集如下。
ProductModelID Result
-------------- ---------
19 <Prod ProductModelID="19">
<pd:Summary xmlns:pd="https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription">
<p1:p xmlns:p1="http://www.w3.org/1999/xhtml">Our top-of-the-line competition mountain bike.
Performance-enhancing options include the innovative HL Frame,
super-smooth front suspension, and traction for all terrain.
</p1:p>
</pd:Summary>
</Prod>
25 <Prod ProductModelID="25">
<pd:Summary xmlns:pd="https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription">
<p1:p xmlns:p1="http://www.w3.org/1999/xhtml">This bike is ridden by race winners. Developed with the
Adventure Works Cycles professional race team, it has a extremely light
heat-treated aluminum frame, and steering that allows precision control.
</p1:p>
</pd:Summary>
</Prod>