I did some research but everywhere is not vert clear. Looks like UPDLOCK does not hold the select too. TABLOCK is not clear.

From what I understood I have to use...

The most important thing is to completely block the 2nd client from even doing a select on the table until the first one is ready so that he will get the next PIN.

 Maybe...

Thanks man!

I will try it out and let us know how it went.

Cheers

Stefan