Amazing! Let's summarize what we've learned.

We can:

• Insert data using NULLs for unknown values in a row:

  INSERT INTO Student 
  VALUES (21, N'Tom', NULL, N'Muller');
  

• Change values using NULL and UPDATE:

  UPDATE Exam 
  SET WrittenExamScore = NULL
  WHERE Id = 5;
  

• Change a value in a column or delete a row if the column contains a NULL:

  UPDATE Student
  SET LastName = N'unknown' 
  WHERE LastName IS NULL;
  
  DELETE FROM Student 
  WHERE LastName IS NULL;

• Update or delete using AND and OR to meet certain conditions:

  DELETE FROM Exam 
  WHERE Subject = N'Spanish' 
  AND (WrittenScoreExam IS NULL OR OralScoreExam IS NULL)

• List columns with the Inserted or Deleted prefixes:

  UPDATE Student
  OUTPUT Inserted.FirstName, Inserted.LastName,
  Deleted.FirstName, Deleted.LastName
  SET FirstName = N'Alan', LastName = N'Stanley'
  WHERE Id = 12;