The argument must be a time, timestamp, or a valid character string representation of a time or timestamp that is not a CLOB, LONG VARCHAR, or XML value. The result of the function is a large integer. If the argument can be null, the result can be null. If the argument is null, the result is 0.
The other rules depend on the data type of the argument specified:
The column RECEIVED (timestamp) has an
internal value equivalent to 2005-12-25-17.12.30.000000. To determine return
only the seconds part of the timestamp, use the following syntax: