Returns the day of the week in the argument as an integer value in the range 1-7, where 1 represents Monday.

The schema is SYSFUN.

expression

An expression that returns a value of one of the following built-in data types:
a DATE, TIMESTAMP, or a valid character string representation of a date or timestamp that is not a CLOB.
In a Unicode database, if a supplied argument is a graphic string (except DBCLOB), it is first converted to a character string before the function is executed.

The result of the function is INTEGER.
The result can be null; if the argument is null, the result is the null value.