The specified number must be a DOUBLE
PRECISION number.
- If the specified number is NULL, the returned value is NULL.
- If the specified number is equal to a mathematical integer, the returned
value is the same as the specified number.
- If the specified number is zero (0), the returned value is zero.
- If the specified number is less than zero but greater than -1.0, the
returned value is zero.
The returned value is the smallest (closest to negative infinity)
double floating-point value that is greater than or equal to the specified
number. The returned value is equal to a mathematical integer. The data type
of the returned value is a DOUBLE PRECISION number.