Semidifference via EXCEPT and JOIN - SQL
SELECT *
FROM (SELECT StudentId
FROM IS_CALLED
WHERE Name = 'Devinder'
EXCEPT DISTINCT CORRESPONDING
SELECT StudentId
FROM IS_ENROLLED_ON
WHERE CourseId = 'C1') AS T1
NATURAL JOIN IS_CALLED
The NOT IN expression above appears to be testing for the appearance of a character string in a table, but in fact the first operand in this context is short for ROW(StudentId)