How can a weak entity be related to weak entity?

Question

As we can see in this image, ATTENDANCE entity is related to TRANSCRIPT entity? But how can entities in TRANSCRIPT be identified if there is no primary key in ATTENDANCE? Is the image wrong?

Answer 1

Let's break it down in simple form. Suppose you have an strong entity A (i.e. Student in your case) which is participating with weak entity B (i.e. Attendance). So now, both of them will act as strong entity and can participate with other weak entity C (which is Transcript).

But how can entities in TRANSCRIPT be identified if there is no primary key in ATTENDANCE?

Now, the primary key of STUDENT combined with partial key of ATTENDANCE will act as primary key for participating in a relationship with TRANSCRIPT.