Oracle Newbie - SQL question

Hey everyone,

Just getting my feet wet with Oracle and I have run into a question I was hoping to get some help with.

I am currently studying for the Oracle SQL cert and came accross this question:

"Display the last name, hire date and the day of the week on which the
employee started. Label the column DAY. ORder the results by the day of the week starting with Monday"

My question concerns the answer supplied in the text:

"SELECT last_name, hire_date, TO_CHAR(hire_date,'fmDay')
FROM employees
ORDER by TO_CHAR(hire_date -1,'d')"

I don't understand the ORDER BY clause.

Specifically:

1. "hire_date -1" - My understanding is that Oracle's day 1 of a week is Sunday. It doesn't seem intuative to use "-1" to move a day forward? Am I misunderstanding something?
2. 'd' - What does this represent? I had assumed "day" but that substitution results in 'some other' weird grouping I don't understand. (ie. it groups all the days of the week but in no apparent order)

Thanks in advance for any help!

Jon Received on Wed Jul 17 2002 - 11:19:58 CDT