>>-WEEK--(--expression--)--------------------------------------><
The schema is SYSFUN.
Returns the week of the year of the argument as an integer value in range 1-54. The week starts with Sunday.
The argument must be a date, timestamp, or a valid character string representation of a date or timestamp that is neither a CLOB nor a LONG VARCHAR.
The result of the function is INTEGER. The result can be null; if the argument is null, the result is the null value.