question was how many entries for citibike.trips.tripduration =null. and I queried out the answer to 3 but showing as wrong answer.
Please check/read your question carefully again and notice the output from your query
You will know the reason
Hello, did you find out why you got it wrong? I would read the question again and notice that it says null, but also does not include those where the field does not exist.
Same issue here. The output of the query is pretty clear, and my query is correct, and yet, it shows wrong. Now I won’t get a perfect score without it being my fault.
Please read the question carefully. Notice the second statement which says you have to ignore those documents which do not have tripduration key.
The concept behind this has been discussed in the video lecture - Chapter 3: Element Operators.
Hope it helps!
Curriculum Services Engineer