Exclude values from resident

[YanivZi]

I am trying to exclude the math courses equal from Student after using subfield but I got error "StudentsExclude.%Key not exists". what i have done wrong?

Students:
LOAD
%Key,
FirstName,
LastName,
Courses, 
Gender,
BirthDay

RESIDENT FACT

StudentsALL:
%Key, 
SubField(Courses, ';') AS Course

RESIDENT Students
STORE StudentsALL INTO [lib://DEMO/StudentsALL.QVD](qvd);

StudentsExclude:
LOAD DISTINCT %Key
RESIDENT StudentsALL
WHERE Course= 'Math';

StudentsExcludeMath:
LOAD *
RESIDENT Students
WHERE NOT Exists(StudentsExclude.%Key);

STORE StudentsExcludeMath INTO [lib://DEMO/StudentsExcludeMath.QVD](qvd);

[Chanty4u]

Change your load script 

StudentsExcludeMath:

LOAD *

RESIDENT Students

WHERE NOT Exists(%Key);

[marcus_sommer]

This: StudentsExclude.%Key indicates that any qualifying is applied. I suggest to remove it completely because it's very seldom an added value (only in specific cases for experienced users) else it will cause a lot of trouble.

[Anders_Eriksson]

Excluding the qualification will not solve the problem that is asked about.
Sure the script will run but exclude everything since every %Key already exists!
I suggest this;

StudentsExclude:
LOAD DISTINCT %Key as %ExcludeKey
RESIDENT StudentsALL
WHERE Course= 'Math';

StudentsExcludeMath:
LOAD *
RESIDENT Students
WHERE NOT Exists(%ExcludeKey, %Key);