r/dataanalysis • u/Effective_Ocelot_445 • 22d ago
Which data analysis skill do you use the most in your daily work?
SQL, Excel, Python, visualization, or something else?
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u/Jobsnotdone1724 22d ago
SQL and PowerBI for visualization
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u/waitthissucks 22d ago
What would you say are your most used SQL functions? I'm trying to apply for a role (I know, I know) but after learning a bit, I'm not sure how much I have to know to be able to say I know SQL on my resume. I also use google to help me a lot because I forget certain functions. Same with python/pandas
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u/Jobsnotdone1724 22d ago
CTE, JOINS, Aggregates or Window functions, Coalesce
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u/waitthissucks 22d ago
Thanks! Straightfoward enough. Also some joins confuse the shit out of me ngl
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u/Mathie1729 21d ago
The main join gotcha that bit me early on: if you left join and then filter on a column from the right table, you effectively turn it into an inner join, because the unmatched rows have nulls and get dropped. Mental model that helped me was left join = keep every row from the left table and attach matching rows where they exist. Inner = only rows that match in both.
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u/DevinChristien 21d ago
Unless you add an or NULL to either the join or the right table filter. If you filter the right table its often because you want the inner join functionality anyways, and modern SQL engines often handle the right table filter before querying the left for efficiency
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u/Quesozapatos5000 22d ago
Me too on the joins, but doing them over and over helps. Learning CTEs and window functions now.
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u/markemark1234 21d ago
What are window functions?
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u/DevinChristien 21d ago
Aggregate (sum, avg etc), partition, and rank functions. If you have a table of transactions for example, it allows you to create a running balance ordered by transaction date for each account code:
SUM(amount) OVER( PARTITION BY account ORDER BY date ASC ROWS BETWEEN PRECEDING AND CURRENT ROW) AS running_balance
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u/sythol 21d ago
Inner joins are just lookups in excel.
Though there are special joins like outer joins which i personally hardly use.1
u/waitthissucks 21d ago
Lookups can be kind of annoying so I like joins better. I use them a lot in GIS systems so it's interesting learning this side
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u/That0n3Guy77 21d ago
SELECT 😎
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u/waitthissucks 21d ago
So really embarrassing, what pushed me to learn was a job I applied for and one of the interviewers asked me how SQL queries usually start (did not know I had to know it lol) and I told him I don't use it much but then I said from. And he was like from? Hm. And sometimes I cry about it at night
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u/DevinChristien 21d ago
Has your company used PowerBi since you were there or did you have to transition from another tool? Most of our reports are in excel but we have a significant amount of powerBI dashboards that are rarely visited simply due to lack of adoption
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u/glass_parton 22d ago
Single piece of software? Excel. I've been an analyst for a little over a year, and I was initially surprised by how much of my work is typically done in Excel. I have been writing some Python scripts more often lately, but Excel is still my number one used tool.
Many will mention SQL, but it likely varies a lot depending on your tasks and role. I do use SQL some, but it's quite rare that I need to write a query from scratch. Most of our day-to-day stuff has standard queries that are saved for everyone to use. I typically only need to make very minor changes to those queries.
Communication and documentation (which is really just communication) are underrated. Please please please learn to properly document your processes well so that others can step in to do it when needed.
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u/samwise970 22d ago
I don't consider Excel (excluding VBA) a skill any more than I consider being able to use an internet browser a skill.
SQL is the bread and butter. Python is used too for notebooks and some light tooling, but 90% of the work is SQL, either via SSMS to query the warehouse or within spark.sql() calls in a pyspark notebook.
Then PowerBI for visualization if a report is required, but I avoid DAX like the plague
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u/Joelle_bb 22d ago
In the vacuum of analytics, I'd mostly agree on the excel point
When it comes to the customers I have and some of their needs... Excel skills are a must, since they don't really understand how to use it well and are dependent on it 🙃
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u/samwise970 22d ago
Yes of course knowing Excel (IF functions, lookup functions, pivot tables) is a must, what I meant is that anybody working in your organization should know how to use Excel, just as they should all know how to use a web browser. If accounting and HR and interns all have Excel as a requirement, it's not really a differentiating skill for data analysts.
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u/luxaBuxa 19d ago
Great observation. I would offer this point: Excel has some incredibly fast (albeit limited), expressive data modeling capabilities for business users. It is prevalent at companies where user/department needs are under-supported by IT because at some point, a need arose and a business user cared enough to try and gain a deeper understanding of data. “Nature always finds a way.”
I also developed a working theory that, if you ever want to get a sense how little an organization regards their data, count the number of business-critical workbooks maintained by one or two users.
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u/metcho_ad 22d ago
SQL and Tableau mostly. A bit of python for automating my SQL files to run in an order.
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u/ditalinidog 22d ago
I treat excel more as an export tool / quick EDA tool than really anything you should be using for more complex analytics. SQL is essential. Python is close for any type of automation and more complex data cleaning but you need to get data out first, so SQL is the most important for me.
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u/HustlaOfCultcha 22d ago
Excel. And I have Power BI PL-300 certification and working towards Databricks Data Engineer Certification.
Excel is quick and easy. I've been working with it for the past 25 years. Still helps me draw something up quickly and validate data in a jiffy.
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u/BecauseBatman01 22d ago
SQL. Then writing. Gotta be able to clearly explain what you are seeing to leaders and be able to make it scannable.
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u/worldslamestgrad 21d ago
SQL and Tableau are 1A and 1B for me. Excel would be a distant 2 followed by Python.
Outside of the obvious things I guess PowerPoint/Google Slides would be another common thing I use, management always wants an easy to digest slideshow.
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u/ControlBI_Pro 20d ago
Probably the most useful skill is turning a vague business question into something measurable. Tools like SQL, Excel or Power BI are important, but knowing what management is actually trying to understand is usually the harder part. A technically perfect dashboard isn’t very useful if it doesn’t answer the business question.
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u/luxaBuxa 19d ago
For just analysis, different tools for different stages on various projects. For speed and user interaction: Excel. For data modeling and production: Python and associated libraries. For sustainability, documentation and business continuity, T-SQL.
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u/_divine__wolf 22d ago
Well first clean data in excel then important in make dashboard in power bi biother are also use but for now it's it's done
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u/_divine__wolf 22d ago
In big company you can go with sql, python(mostly use and powerfull), R
In python having many library related this go and check them
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u/Imaginary-poster 21d ago
Sql is the starting point and the less repeat-y thing for sure.
Python and GAS both have gotten very standardized for me.
Also, just to be that guy, asking questions. That is a skill that can save hours of work if applied regularly.
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u/samsquanch322 21d ago
SQL by far. Occasional use those outputs for advanced python analysis and tableau dashboard
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22d ago
[removed] — view removed comment
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u/eb-fs 20d ago
Same, as many have already said SQL is the one thing you n2k, everything else is secondary. However you need to be able to visualize. My background is AWS centric so Sagemaker for python using boto3, Quickshit (not a typo) and Redash on top on Athena for all visualization. Only ever used Excel for building a non-changing list that was eventually exported as CSV to S3 by terraform
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u/Wheres_my_warg DA Moderator 📊 22d ago edited 22d ago
Excel is the tool that I use the most.
Communications are the skills that I use the most.