Resolved: Explanations to questions 15 and 29

I agree with Alessandro when it comes to copying the code. It's not a problem when  you show a code with blanks to answer it on the first question. However, using that whole code to run on the next one is very time consuming (I'm referring to Practice Exams).

In other courses, they let us download a file that contains the code/data. You can just send a file where its code have blanks in it. With that, we can focus more on the problem, and typing speed wouldn't matter as much. Why is it not implemented here?

Please let us take the given time to solve problems, not to write code.

Thanks,
Carl

Hi Alessandro and Carl,

Thank you very much for your feedback.

1. @Alessandro: Thank you very much for your suggestion, as well as mentioning the organisation of the final exam from our part. May I please ask you - while checking your answers (after having submitted the exam), aren't they sufficient in understanding why a given answer has been the correct one to select?
   Please feel free to revise the relevant lectures from the course on the given topic in the meantime. Thank you!

2. Regarding the copying of the code.
   After long discussions and testing sessions, we, from the 365 Team, have decided, that the ability to type code correctly is crucial in a professional environment. Yes, it is true that we will often copy and paste code, but this sometimes takes away from our ability to dig deeper into a problem and overlook a potential error.
   Therefore, we've decided that we want everybody that has completed our course and final exams to be people that are autonomous and independent when typing their own code.
   In addition, please do consider that the time you've been provided to submit a given exam takes into account the time required to type the code necessary to answer the questions of a given exam. This, of course, has been tested multiple times as well.

Hope this helps and looking forward to your answer about 1), Alessandro. Thank you!
Kind regards,
Martin

Good evening. Honestly, I don't remember anymore very well what were the problem. I have just completed the following course in the meanwhile. But I remember that the explanation to the solution wasn't sufficient to understand why the last answer to question 15 ("DATEDIFF(record_label_contract_start_date, record_label_contract_end_date) > 3652;") is wrong and why the answer "CREATE INDEX i_star ON artists(*);" in question 29 is wrong.
Thank you

Hello,
I also finished the course, and would have a hard time recalling some details right off the bat.

@Martin: I agree that there is no better way to instinctively write correct code than writing code itself. Maybe you can consider extending the time limit for the course exams that involve writing our own code, just to factor in the time consumed in typing.

Hi Alessandro and Carl,

Thank you very much for your honest feedback.
I have quickly checked the course exams (which I think is what you are referring to; but even if you are referring to the final exams,I hope my answers will still help you obtain an indication on how to interpret the exercise solutions). Without giving too much away from the exams, I'd say:

1. Please focus on the use of the TIMESTAMPDIFF() and DATEDIFF() function and the way they operate (i.e. how many arguments are required to apply both functions, what result/type of value they display, how they apply a subtraction).

2. Please revise the difference between a single-column and a composite index in MySQL. Here's a reference from the course: https://learn.365datascience.com/courses/sql/mysql-indexes/

Hope this helps.
Kind regards,
Martin

About the 2nd point, maybe I couldn't use "*" between parentheses because it's important to specify the order of the columns? I have rewatched that lesson, but it doesn't specify if I can use * or not

About the first point, I have searched on the web and it seems that both TIMESTAMPDIFF() and DATEDIFF() make use of 3 arguments, but I seem to remember that something like "DATEDIFF(record_label_contract_start_date, record_label_contract_end_date)" also worked when I tested it. It seems that both the functions do the same thing, they require the same number of arguments, they both return an integer (or maybe a float? I don't remember anymore), so it's not very clear what is the difference. Thank you

Hi Alessandro,

1. Point 1. Please be careful when using TIMESTAMPDIFF() and DATEDIFF() - these functions are not interchangeable and function differently. Also, the number of arguments may differ. DATEDIFF(), for instance, requires 2 arguments, while TIMESTAMPDIFF() - 3.

2. Point 2. Spot on! Thank you for pointing this out! The order in which we write the columns in MySQL Indexes matters.

Hope this helps.
Best,
Martin

Thanks. Sorry for changing the subject: is there any reason why nobody answers any question in chapter 8 of the data scientist's career track? I refer to the chapter "Deep learning with Tensorflow 2.0". Thank you

Hi Alessandro!

You are very welcome.
Regarding changing the subject - not at all, it is on point. Can you please share a link to the question you've posted, so that we can look into it soon. I would be happy to send it over to those who can assist about that course.
Thank you.

Looking forward to your answer.
Best,
Martin

Good morning. I have posted 10 questions in that chapter during the last few weeks, so I can't put here the link of every question. For this reason I decided to put here the first question I made for that chapter:
https://learn.365datascience.com/question/why-spam-filtering-is-not-an-instance-of-machine-learning/
From there onwards, you can find the other questions I have made under various lessons. Thank you!

Q15 is really a good one, it confused me as well...

After checking out the syntax in both function, one will see that,

For DATEDIFF():

DATEDIFF(end_date, start_date)

FRO TIMESTAMPDIFF():

TIMESTAMPDIFF(unit, start_datetime, end_datetime)

So the 4th answer is definitely not correct, because it's given order is wrong.

Hope this helps!

Hi Chun!
Please accept my apologies for the belated reply on this topic. 

After a new inspection of the issue, we figured out that we've missed an AND operator in the task.

So, it is as if we were asking what to add after

...
WHERE

   no_weeks_top_100 > 15 AND
_______________ (1) ___________________

Of course, we should update the exam. I've passed on the technical issue to my colleagues. We will update the question as soon as possible.
Thank you once again for pointing this out and sorry for any inconvenience this may have caused to your learning process.
Hope this helps.
Kind regards,
Martin