记sqlServer获取文件后缀名

-- ----------------------------
-- function structure for getFileName
-- ----------------------------
IF EXISTS (SELECT * FROM sys.all_objects WHERE object_id = OBJECT_ID(N'[dbo].[getFileName]') AND type IN ('FN', 'FS', 'FT', 'IF', 'TF'))
	DROP FUNCTION[dbo].[getFileName]
GO

CREATE FUNCTION [dbo].[getFileName]
( @FileName AS varchar(255) 
)
RETURNS varchar(225)-- nvarchar
AS
BEGIN
	-- routine body goes here, e.g.
	-- SELECT 'Navicat for SQL Server'
	declare @name varchar(255)  
  declare @length int
	declare @i int
	set @length = LEN(@FileName)
	set @i =2
	set @name ='????'
	WHILE (@i < @length )AND( @length<> 0)  BEGIN
	 set	@name = RIGHT(@FileName, @i)
	 IF LEFT(@name,1) = '.'
		BEGIN
		set @name = RIGHT(@name, @i-1)
		set @i = @length
		END
	 else 
		BEGIN
			SET @i = @i+1
			SET @name = '???'
		END
END

	
	
	RETURN @name
END
GO

使用

        SELECT
               a.file_name,
               dbo.getFileName(a.file_name)
        from
            base_resource a