The argument must be a date, timestamp, a positive number less than or equal to 2,932,897, a valid string representation of a date or timestamp, or a string of length 7 that is not a CLOB, LONG VARCHAR, or XML value. If the argument is a string of length 7, it must represent a valid date in the form yyyynnn, where yyyy are digits denoting a year, and nnn are digits between 001 and 366, denoting a day of that year. The result of the function is a date. If the argument can be null, the result can be null; if the argument is null, the result is the null value.
The other rules depend on the data type of the argument specified:
This example results in an internal representation of '1988-12-25'.