A common question I have seen good people get tripped up on. Remember KISS – Keep it Simple Stupid.
Don’t let the question trick you into overthinking. For a SQL query you need a SELECT command (what do we want), a FROM (what table is it in) and if you want to go for the extra credit point, throw in a WHERE (its our filter)
Below is a list (in no particular order) of real interview questions I have either asked, been asked, or saw asked in a real interview. While everyone has their own take on interview advice, mine is pretty clear cut. Answer the question, nothing more nothing less. Don’t get caught up in the trap of trying to add too much detail. Unless specifically asked for more detail, the interviewer more often than not just wants to make sure you have a grasp of the concepts.
1. Explain the difference between Regression and Classfiers:
If experience has taught me anything, it is that while companies and organizations have gotten much better at collecting data, most of this data is still just stored away in unstructured data stores. So while the data is “technically” there, it is not a whole lot of use to anyone trying to build a report or create a machine learning model. In order to get actually use out of all the data being stored, it needs to organized into some sort usable structure: Enter the Data Architect.
Data Architect is a job title I have held on multiple occasions throughout my career. My best description when explaining the job to other people is that I was kind of like a data janitor. You see, everyone takes their data and dumps it into the storage closet. So you find some billing data on the second shelf, tucked away behind employee HR records. The floor is cluttered with server logs and six years worth of expense reports stored as PDFs with completely useless names like er123.pdf.
As a data architect, it was my job to try to organize this mess and put the data into some sort of structure that lends itself to reporting or modeling. So data architects have to be well versed in data modeling, data storage, and data governance.
Data modeling is basically taking raw data dumps and organizing them into structure that fit the needs of company. It could involve creating an HR database like above or creating a series of aggregated tables designed for reporting or dashboarding. It is the job of the data architect to best fit business needs to a data platform: be it a transactional database, a data warehouse, or perhaps a data lake.
Data architects also need to address data storage. While I often defer to the server crew in the IT department, as a data architect I do advise on to how and where to store data. Cloud infrastructure and cheaper faster disk storage has made a lot of data storage decisions easier, but it is good to have a working understanding of storage platforms.
Data governance is all about how the data is managed from a regulatory and security standpoint. It is the practice of deciding who can have access to what data. Can some data be “outside facing” versus should some data sit behind multiple firewalls in a DMZ zone.
You will often work hand in hand with Legal and Security departments when figuring out how data governance practices will be implemented.
A past co-worker of mine by the name of Antonio Ivanovski (AI) has written a free e-book giving some great advice on how to get your foot in the door as a data professional and how to make some smart moves to really improve your job satisfaction as well as earning potential. He not only talks the talk, but walks the walk. He has managed to quadruple his salary in a little under 5 years moving from UPS to Verizon, and now (as of this writing) he is working as a Senior Data Analyst for Google.
If you are looking to get into the field or looking for advice on how to move up, his free e-book is worth a read.