I am taking my first DB course and I need to rewrite the followingasserting usin

Question

I am taking my first DB course and I need to rewrite the followingasserting using the EXCEPT statement

Code:

CREATE ASSERTIONNoEmptyCourses
CHECK (NOT EXISTS (
SELECT * FROM Teaching T
WHERE
NOT EXISTS (
SELECT * FROM Transcript R
WHERE T.CrsCode = R.CrsCode
AND T.Semester = R.Semester)
))
Here is what I got:
Code:

Check ( Exists (
Select CrsCode, Semester From Teaching
Except
Select CrsCode, Semester From Transcript
))
So it will check the existence of the course offering at somesemester but nobody register in it (not in any student'sTranscript).

Am I right? Thank you in advance for pointing out my mistakes. Code:

CREATE ASSERTIONNoEmptyCourses
CHECK (NOT EXISTS (
SELECT * FROM Teaching T
WHERE
NOT EXISTS (
SELECT * FROM Transcript R
WHERE T.CrsCode = R.CrsCode
AND T.Semester = R.Semester)
)) Code: CREATE ASSERTIONNoEmptyCourses
CHECK (NOT EXISTS (
SELECT * FROM Teaching T
WHERE
NOT EXISTS (
SELECT * FROM Transcript R
WHERE T.CrsCode = R.CrsCode
AND T.Semester = R.Semester)
)) Code:

Check ( Exists (
Select CrsCode, Semester From Teaching
Except
Select CrsCode, Semester From Transcript
)) Code: Check ( Exists (
Select CrsCode, Semester From Teaching
Except
Select CrsCode, Semester From Transcript
))

Explanation / Answer

{ EXCEPT }

  { <query_specification> | (<query_expression> ) }

      Select CrsCode, SemesterFrom Teaching

   Except

      Select CrsCode, SemesterFrom Transcript

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