function to remove special characters in sql

Create function [dbo].[RemoveCharSpecialSymbolValue](@str varchar(500))  
returns varchar(500)  
begin  
declare @startingIndex int  
set @startingIndex=0  
while 1=1  
begin  
set @startingIndex= patindex('%[^0-9.]%',@str)  
if @startingIndex <> 0  
begin  
set @str = replace(@str,substring(@str,@startingIndex,1),'')  
end  
else break;  
end  
return @str  
end