SQL temp tables

how do u keep the results after doing a join and getting some records returned. I then need to get a count of all the nulls in a particular column of those records returned. But I can't seem to figure out how to get a count of those null records. The temp table is out of juice at that point?

Help?

select column names
into #temp1
from table1 left join table2
on table1.colX = table2.colY
where /*specify where clause*/


select count(*) from #temp1
where colZ is null
' gives the count of records