Test FAQs - PLEASE READ BEFORE ATTEMPTING TO ANSWER
YunoJuno is a fast-growing startup with a heavy emphasis on self-reliance. How you fit in to our environment is important, and this test is designed to represent a real-world challenge of the type with which you will be faced in the job.
We are not testing you solely for your technical knowledge - we want to see how you would approach the job itself. This means reading the instructions, possibly having to look a few things up online, maybe even installing some software. Doing whatever it takes. These FAQs have been put together from some of the questions we have received from candidates. Please read carefully.
Q1. What should I do if I don't have a database installed locally?
Install one. Postgres is free, MySQL is free, SQL Server Express is free. If you can't install a free database server, configure it locally and import a CSV into it, you won't pass the test. Postgres is preferred.
Q2. What exactly am I being asked to do?
Write a single SQL query that outputs the data shown in the screenshot.
Q3. Can I use R or Excel to complete the test?
No. See Q2 above; this is a SQL test.
Q4. R is better suited to this kind of problem, why can't I use it?
This is a real example of what you will be asked to do. We present data using Periscope, which requires that you can write SQL against a read-only Postgresql database. If you pass the test and come for interview, we'd love to hear how you would have done the test with R.
Q5. Will I ever get to use R in the job?
Yes, quite possibly. It's just that the first task is getting data into charts in Periscope, and that means SQL first, R later.
Q6. Can I use temporary tables?
No. We run our reporting against a read-only copy of the live database. You will not have access rights to create temporary tables.
Q7. What's a CTE?
You don't need to use a CTE to pass this test, but you do need to know what it means, and why you might want to use one.
Q8. Anything else I should be aware of?
We subscribe to the mantra that code is read more often than it's written. This means that whilst getting a working SQL query is the first requirement, how you've written the query is also important. The following may be useful:
- Use spaces not tabs
- Do not over-indent
- Comment liberally
The test is evaluated by copying your answer, pasting it into Periscope and clicking on the Run button. If it outputs the expected data, you've passed, and we'll then take a look at the code itself. If it doesn't run then we won't.
The tables in the test database against which we will run your test are
state_transitions. Please use these same
names, otherwise the test won't pass.