select tabname,
count(*)
from sysextents
where dbsname = 'DATABASE'
group by 1
Or summarised by dbspaces
select substr(DBINFO("DBSPACE",partnum),1,10) DBSpace,
dbsname[1,10] Database,
tabname[1,15] Table,
sum(pe_size) tot_space,
count(*) no_of_exts
from sysptnext, systabnames
where pe_partnum = partnum
and tabname != "TBLSpace"
group by 1,2,3
order by 1,4 desc