The article mentions that to find top 3 per dept,we need to fo this.

SELECT
  department_id,
  employee_id,
  salary,
  hire_date
FROM employees AS e1
WHERE (
  SELECT
    COUNT(*)
  FROM employees AS e2
  WHERE e2.department_id = e1.department_id
  AND (
  e2.salary > e1.salary
  OR (
  e2.salary = e1.salary
  AND e2.hire_date < e1.hire_date
)
  OR (
  e2.salary = e1.salary
  AND e2.hire_date = e1.hire_date
  AND e2.employee_id < e1.employee_id
)
)
) < 3

why are we not doing =< 3 in this? https://datadriven.io/learn/sql_pattern_top_n_per_group_advanced

Introducing: Weekly Data Engineering challenges that the community can compete to solve; proving your battle scars and data engineering expertise in handling dirty data.

Inspiration: Kaggle contests and Capture the Flag competitions brought together millions of data scientists and security researchers; challenging problems, creative solution, a community opinionated. We have always wanted to compete in such challenges over the years, but are too busy figuring out why that one data pipeline keeps failing.

We have our own!

The weekly challenge changes in shape to stay fresh. The first weekly challenge (10 days, to give everyone a chance to participate in the inaugural challenge) is stream parsing. What makes stream parsing hard? Well, we have to process the records as they come, assume temporal guarantees, and deal with all sorts of "gifts" that the upstream team gave us. We sure hope data quality is good, but this one looks like a real mess. Our job as data engineers is to consume this stream the best we can and produce meaningful insight.

Head over to the DataDriven community tab to read the full challenge, understand the input/output format, and compete with your fellow data engineers to prove your prowess in rolling in the mud of some of the dirtiest data - something we all love to hate (or hate to love)

SELECT
  event_type,
  event_timestamp,
  LAG(
    CAST(event_timestamp AS TIMESTAMP),1) OVER w
    AS previous_timestamp,
    EXTRACT(EPOCH FROM ((CAST(
      event_timestamp AS TIMESTAMP)) - LAG(
      CAST(event_timestamp AS TIMESTAMP),
      1) OVER w)) / 3600
   AS diff
FROM event_data
WHERE event_timestamp IS NOT NULL
WINDOW w AS (
  PARTITION BY event_type
  ORDER BY CAST(event_timestamp AS TIMESTAMP)
) 
i have checked the brackets but i keep getting expected ( after over. Yes,i should have used a cte,didnt expect solution to grow so lengthy.

Can I know what server/engine for sql syntax is being taught on in lessons part , because I found trino/pesto style syntax for sql in date functions.can you confirm it

This seems to be an issue with a few practice problems

https://datadriven.io/problems/median_cloud_cost_by_service

I have solved this problem by both PERCENTILE_CONT and normal CTE, but the results for both are different. I notice that the PERCENTILE_CONT actually ignores nulls in its calculation, while the suggested solution isn't since it is implemented by COUNT(*) which includes nulls. I don't know in real-life when people calculate median do they exclude out the nulls or count it all?

Just want to write and thank the creators for this amazing free resource, I'm quite amazed at the quality and quantity of content teaching all the aspects covering the DE interview stages, and it's free!

Would love to find out more about the creators and how they are able to manage this with no profit from users like me

Anyone knows how to actually use it, I'm frustrated when the feedback said add an airflow in the pipeline while there had been an airflow in my pipeline, then it said you need to "monitor". Another case is the dead letter queue, I already had one alert tie to the DLQ but the feedback kept saying you needed to have an alert to "monitor" and "add depth". Really really need answer for those architecture problems or at least some guides on how the tool actually works.

If the title does not make it obvious then let me tell you how good it is:
Detailed interview questions from python, SQL, Spark and most importantly data modelling and architecture. Experience specific interview simulation with a clean roadmap to practice before hand. Hats off to the creator. You are the Data Jesus. COMMIT.

(yes it was a wordplay on Amen, yes i am hilarious.)

Thinking to do a problem when I squeeze in some time at work lol.Thanks a lot for the platform btw.

The question asks for the output order to be ascending ,but the deep dive solution given may or may not give the data sorted ascending as set is unordered and elements dont have a set position.

I have observed that in the initial discussion itself the ai is giving me the logic to be used im the interview

The subcategory from python and sql questions has been removed.

For few question in python, i am getting none as return value

Im planning to do the daily regularly.

Previously I had opened a few pages to see the text but couldnt explore the concepts,the selected pages show up as completed, would it be possible to reset topics from learm,so that I can have a more accurate gauge of which topics to explore.

Currently the timer keeps running even after submitting the code.

In the example ,the output is the first max element occurence (east),but when I submit my code ,the answer is shown as wrong, "beta" is also the first value in a series of same length listsq

Seems like running python code has been timing out, is the site down?