   CONV(N,from_base,to_base)
Converts numbers between different number bases.  Returns a string
representation of the number N, converted from base from_base
to base to_base.  Returns NULL if any argument is NULL.
The argument N is interpreted as an integer, but may be specified as
an integer or a string.  The minimum base is 2 and the maximum base is
36.  If to_base is a negative number, N is regarded as a
signed number.  Otherwise, N is treated as unsigned.  CONV() works
with 64-bit precision.
