Selecting file extensions in sql server

gistfile1.sql

--Distinct File extensions
SELECT DISTINCT Reverse(Substring(Reverse(originalfilename), 1, 
                                        Charindex('.', Reverse(originalfilename) 
                                                ) - 1)) AS FileExt 
FROM   [file] WITH (nolock) 
WHERE  Charindex('.', originalfilename) != 0 
       AND Reverse(Substring(Reverse(originalfilename), 1, 
                       Charindex('.', Reverse(originalfilename) 
                               ) - 1)) NOT IN ( 'csv', 'pdf', 'htm', 'html', 
                                                'xls', 'xlsx', 'ppt', 'pptx', 
                                                'doc', 'docx', 'txt' ) 
ORDER  BY Reverse(Substring(Reverse(originalfilename), 1, 
                            Charindex('.', Reverse(originalfilename) 
                                    ) - 1)) 

--Get the count of a specified file extension                                    
SELECT Count(*) 
FROM   [file] with (nolock) 
WHERE  Charindex('.', originalfilename) != 0 
       AND Reverse(Substring(Reverse(originalfilename), 1, 
                       Charindex('.', Reverse(originalfilename) 
                               ) - 1)) = 'pdf' 

--Average file size for a given file extension                                    
SELECT Avg(filesize) 
FROM   [file] WITH (nolock) 
WHERE  Charindex('.', originalfilename) != 0 
       AND Reverse(Substring(Reverse(originalfilename), 1, 
                       Charindex('.', Reverse(originalfilename) 
                               ) - 1)) = 'pdf'

--Total file size for a given file extension                               
SELECT Sum(filesize) 
FROM   [file] WITH (nolock) 
WHERE  Charindex('.', originalfilename) != 0 
       AND Reverse(Substring(Reverse(originalfilename), 1, 
                       Charindex('.', Reverse(originalfilename) 
                               ) - 1)) = 'pdf'