ms sql 获取字符串首字母

很久没有编写新文章，现在发布一篇自定义函数，针对于ms sql数据库中需要获取字符串首字母，对于需要的朋友希望对你有用，如果你有更好的方法也可以给我留言。函数如下：

--获取字符串首字母
CREATE FUNCTION f_GetPY(@str nvarchar(4000))
RETURNS nvarchar(4000)
AS
BEGIN
--创建临时表
DECLARE @py TABLE(
	ch char(1),
	hz1 nchar(1) COLLATE Chinese_PRC_CS_AS_KS_WS,
	hz2 nchar(1) COLLATE Chinese_PRC_CS_AS_KS_WS
)
--插入匹配介点数据
INSERT @py SELECT 'A',N'吖',N'鏊'
UNION  ALL SELECT 'B',N'八',N'簿'
UNION  ALL SELECT 'C',N'嚓',N'错'
UNION  ALL SELECT 'D',N'哒',N'跺'
UNION  ALL SELECT 'E',N'屙',N'贰'
UNION  ALL SELECT 'F',N'发',N'馥'
UNION  ALL SELECT 'G',N'旮',N'过'
UNION  ALL SELECT 'H',N'铪',N'蠖'
UNION  ALL SELECT 'J',N'丌',N'竣'
UNION  ALL SELECT 'K',N'咔',N'廓'
UNION  ALL SELECT 'L',N'垃',N'雒'
UNION  ALL SELECT 'M',N'妈',N'穆'
UNION  ALL SELECT 'N',N'拿',N'糯'
UNION  ALL SELECT 'O',N'噢',N'沤'
UNION  ALL SELECT 'P',N'趴',N'曝'
UNION  ALL SELECT 'Q',N'七',N'群'
UNION  ALL SELECT 'R',N'蚺',N'箬'
UNION  ALL SELECT 'S',N'仨',N'锁'
UNION  ALL SELECT 'T',N'他',N'箨'
UNION  ALL SELECT 'W',N'哇',N'鋈'
UNION  ALL SELECT 'X',N'夕',N'蕈'
UNION  ALL SELECT 'Y',N'丫',N'蕴'
UNION  ALL SELECT 'Z',N'匝',N'做'
--获取首字母
DECLARE @i int
SET @i=PATINDEX('%[吖-做]%' COLLATE Chinese_PRC_CS_AS_KS_WS,@str)
WHILE @i>0 begin
	SELECT @str=REPLACE(@str,SUBSTRING(@str,@i,1),ch)
	,@i=PATINDEX('%[吖-做]%' COLLATE Chinese_PRC_CS_AS_KS_WS,@str)
	FROM @py
	WHERE SUBSTRING(@str,@i,1) BETWEEN hz1 AND hz2
end
RETURN(@str)
END
go

--示例
select dbo.f_GetPY('获取字符串首字母')
go

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