I'm using a Contains clause for some data that's getting passed from
Reporting Services and I'm having trouble dealing with NULL, which creates a
"Null or empty full-text predicate." error.  

My first thought was to trap it using a coalesce or isnull as in
contains(companynamecolumn,isnull(@report_parameter,'thiswillneverbefound'))

but that didn't work.  I also tried using a case within the contains, also
didn't work.  

I also tried using the OR as in

contains(companyname,'@report_parameter OR "thiswillneverbefound"')

but it took the "report_parameter" literally and even if I missed with the
string literal to fix it I'm guessing it will still choke on the NULL.

The only other idea I had was to use a case before the contains as in

case when @report_parameter is not null then
contains(companyname,@report_parameter) else contains(companyname,'adfdas')
end

but that's not going to fly.

Any ideas?  I'd rather avoid messing with the variable in RS if possible.