TRUNC(number[,length])

The number is rounded as necessary according to NUMERIC DIGITS, and then
truncated or padded so that the result has exactly "length" digits
after the decimal point. If the length is zero or is omitted, then the
result is an integer with no decimal point. The result will never be in
exponential form.

Examples:
   trunc(12.6)      == 12
   trunc(345e-2,1)  == 3.4
   trunc(26,5)      == 26.00000