Substring of a LONG

Hi,

I am storing stories in our database in LONG format. When I pull a few out to show on a web page (using PHP), I only want to pull, say, the first 100 characters, then make a link out of it to the story in full. I tried doing a substr(body,0,100) but got an "Incompatable datatypes" error.
Does this mean the column 'body' must be a varchar2 to be able to do a substr() function in the SQL?
How do I get round this? I don't want to retrieve the whole of each story body, that would be very inefficient.

thanks,

• Kev