Do you mean you want to use some code to identify the columns that only contain nulls so that you can skip them?  If you know which columns are always...

Ed,
Do you have an example of creating constraints the way Gail does, but naming them?  The only examples I have seen require an ALTER TABLE ADD CONSTRAINT style... I...

Probably a silly question, but if you don't name the foreign key, how do you drop it (the easy way)?  Can you name the constraint when you declare it that...

Does it work?  Can you query the table to get the answers you need?

Something like this?

CREATE TABLE dbo.Grades (
    StudentID INT
    ,ExamID INT
    ,Grade TINYINT
    ,StudentStatus VARCHAR(10)
CONSTRAINT pkGrades PRIMARY KEY (StudentID, ExamID)
);
GO

ALTER TABLE dbo.Grades...

Taking a step backward, what is the table supposed to describe / store data about? Are the values {present, absent, disallowed} mutually exclusive?

Why not just put the "absent" or whatever in another column? If you try to stuff everything in the same column, querying your data is going to be a nightmare.

Does your parameter have a default set? If not, and you don't enter anything, the report won't run because the stored procedure can't return any data.

You've been here over 500 times and can't even post an answerable question with proper sample data??? Please read this article and repost.

Create a variable to store the value and then pass it?

Sounds like you could use a Windowing function to do this... this isn't right, but should give you some idea.

SELECT SuperTaskID
, SubTaskID
, ID
, TaskName
,...

I tried running your CREATE TABLE and INSERT scripts, but they wouldn't compile.  Oh wait, there were no scripts.  Hence no useful reply,,,

Maybe I should make this bigger...

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You would just OUTER join your query to the table of internal users.  The result would be that any external users would generate a NULL in the Users table, so...