text: CREATE TABLE IF NOT EXISTS ExamStatus (
      id                  SERIAL        NOT NULL PRIMARY KEY,
      for_exam            INTEGER       NOT NULL, 
      from_student        INTEGER       NOT NULL,
      status              INTEGER       DEFAULT 0,
      created             TIMESTAMP     NOT NULL DEFAULT CURRENT_TIMESTAMP,
      modified            TIMESTAMP     NOT NULL DEFAULT CURRENT_TIMESTAMP,
  
      FOREIGN KEY (for_exam) REFERENCES Exams(id),
      FOREIGN KEY (from_student) REFERENCES Users(id),
      UNIQUE (for_exam, from_student)
  );
  --!!
  DROP TRIGGER IF EXISTS update_examstatus_modified ON ExamStatus;
  --!!
  CREATE TRIGGER update_examstatus_modified BEFORE UPDATE
      ON ExamStatus FOR EACH ROW EXECUTE PROCEDURE 
      update_modified_column();
  