Gerard,
Didn't understand the need but doesn't matter :)
"If nobody else has the file open"
You could do in this case :)

function ZapIt
lparameters tcTableFullpath
local llInUse, lnInUse, lcAlias, ix
local array arrInUse[1], arrUsedIn[1]
lnInUse = aused(arrInUse)
for ix=1 to lnInUSe
    if dbf(arrInUse[ix,1]) == upper(tcTableFullpath)
       use in (arrInUse[ix,1])
       dimension arrUsedIn[iif(type('arrUsedIn[1]')='N',1,0)+;
          alen(arrUsedIn)]
          arrUsedIn[alen(arrUsedIn)] = ix
       llInUse = .t.
    endif
endfor
select 0
if fopen(tcTableFullpath,12) && Nobody else is using - including private datasessions
   fclose(tcTableFullpath)
   use (tcTableFullpath) exclusive
   zap
   use
   if llInUse
   for ix=1 to alen(arrUsedIn)
      use (tcTableFullpath) in 0 alias (arrInUse[arrUsedIn[ix],1])
   endfor
   endif
endif

PS: Untested, not exclusively checking errors, not checking other datasessions, not checking and restorin order etc
Cetin

>Hi Cetin.
>Yes. this is the reason why it should be exclusive.
>So what I want to do is:
>
>
>Sele MyFile
>If nobody else has the file open
> Open it exclusive
> Zap it
>Endif
>Open it shared again
>
>This has come about because of the following:
>
>A file that a match was being done on has say 700,000 records
>If a particular condition arises, a complete rematch needs to be done.
>Up to now , I used a delete all, and re-did the match... it was going to take 2 weeks (yes 14 days we reckoned) non stop processing.
>
>I zapped the file and it took 20 mins !!!
>
>
>regards,
>
>Gerard
>
>
>
>
>>>Hi.
>>>I have all my Tables set up in DE, and Set Exclu is off.
>>>However, there is one case where I need to be able to temporarily open the table exclusively, because I want to Zap the file.
>>>
>>>If I set exclu on, it does not work for tables already opened.
>>>How do I do this for a table that is already opened, Zap the file, and then go back to using it non exclusively.
>>>
>>>regards,
>>>
>>>Gerard
>>
>>Gerard,
>>Impossible. Assuming it was possible for a moment why would you ever want to do that. Think I'm user xx on station yy and have that table open, you zap and suddenly out of the blue the table I'm working on has no records !
>>Cetin