Factorial in SQL
Example for versions
Oracle 10g SQL,
Oracle 11g SQL
Pure SQL doesn’t support loops, recursions or userdefined functions. This example shows one possible workaround which uses

pseudocolumn
level
to construct a pseudotable containing numbers 1 through 16, 
aggregate function
sum
which allows to sum the elements of a set 
and math functions
exp
andln
to replace multiplication (required to calculate the factorial) with addition (provided by SQL).
Note that 0! will not be present in the return, since trying to calculate ln(0) produces an exception.
select t2.n  '! = '  round(exp(sum(ln(t1.n))))
from
( select level n
from dual
connect by level <= 16) t1,
( select level n
from dual
connect by level <= 16) t2
where t1.n<=t2.n
group by t2.n
order by t2.n
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