Indx newbie: please help

Consider the following

--------------------
ASSIGNMENT
- Index : Integer, Unique, NotNull, Primary Key
- Start : DateTime, , NotNull,
- End : DateTime, , ,
- Other : ...

TASK
- Assignment : Integer, Unique, NotNull, Primary Foreign Key
- SubIndex : Integer, , NotNull, Primary Key
- Type : Char(3), , NotNull, Foreign Key
- Start : DateTime, , NotNull,
- End : DateTime, , ,
- Other : ...

TASK_TYPE
- Code : Char(3), Unique, NotNull, Primary Key
- Description : VarChar(20), , NotNull,
--------------------

As u can c the idea is simple...
...an assignment has an INDEX as PK, a start date, an end date and other fields;
...an assignment can have one or more tasks; the relationship is 1:N and is identifying (see next point)
...a task has a SUB INDEX inside the assignment; that is the PK is the assigment it belongs to (also a FK) and an index for that assignment
...a task has also a TYPE, which is a FK to the TASK_TYPE table

Consider also that...
...ASSIGNMENT contains > 1 millions rows
...TASK contains < 10 rows for each assignment (so an average of 5 millions rows)
...TASK_TYPE contains < 10 rows

As far as I know SQL-server creates a CLUSTERED INDEX for any PK, that is
ASSIGNMENT (Index)
TASK(Assigment, SubIndex)
TASK_TYPE(Code)

Do I have to add any other NON CLUSTERED INDEX? I would say I should add the following:
TASK(Assignment)
TASK(Type)

But of course TASK(Assignment) is already part of the CLUSTERED INDEX ASSIGNMENT(Assignment, SubIndex), so I shouldn't add it, right?
What about TASK(Type)?

Or maybe there's a completely different solution?

My main problem is due to the fact that TASK has a composite PK wher one field is also a FK.

Any advice is welcome.

thanks a lot :-)what, exactly, is your main problem? you didn't say what it was :)

i don't think you need any additional indexes, since TASK_TYPE should always be handled in memory (but then, i am not a DBA, eh ;))

by the way, it's not a good idea to name a column "index" as this is a reserved word in a lot of languages|||I'd simply like to know how where to put indexes :)|||okay, put an index on task.type

;)|||I would put the index in the database. Someone might need it, and it would be very embarrassing, if you left it at home.

Joking aside, is there a particular query that is giving problems? Remember that excessive indexing can hurt data modification processes.