Build a star schema from a single flat file
One wide CSV, thousands of repeated names. By the end you have a fact table, two dimension tables, and a model Power BI actually wants.
Power BI
// 38 postsTutorials, tips, and deep dives on Power BI — every post from bianca.codes tagged Power BI.
Power BI posts
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VAR: the DAX keyword that makes your measures readable
A DAX measure that repeats the same subtotal three times isn't thorough, it's a maintenance problem VAR was built to fix.
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Format painter: copy a Power BI visual's formatting in one click
Power BI's format painter copies fonts, colours and borders across visuals in one click, except for one axis setting that quietly breaks chart comparisons.
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Most Power BI dashboards are just decorated spreadsheets
Three slicers and a card don't turn a spreadsheet into a data model, and the columns you didn't build are exactly where it falls apart.
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The dashboard I built that nobody opened
Three months of polish, a great demo, and a usage metrics report that told a very different story once the meeting was over.
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When did the spreadsheet quietly become a database - and why that's a problem
Nobody decided to build a database out of that 80-tab workbook - it ended up doing a database's job without any of a database's guarantees.
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3-Minute Win: Add a 'Last Refreshed' Timestamp to Any Power BI Report in 2 Minutes
The stakeholder emails asking whether the numbers are current stop the day you put the actual refresh time on the report - and a measure with NOW() is not how you do it.
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Star Schema Done Right, Part 4: Migrating a Flat Table to a Star Schema in Power BI
Power Query carves one flat sales table into a fact and three dimensions, you build the relationships, and you prove the numbers didn't move - a restructure you can't validate is just hope.
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If You've Copied the Same Power Query Steps Across Three Queries, You've Made a Mistake
Copying a query and tweaking the copy feels efficient. It isn't - three copies of the same logic is three places to update and three ways for it to drift.
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Build a Reusable Power Query Function That Cleans Any Text Column to Title Case
The same trim-and-title-case steps are copy-pasted across three of your queries - write them once as a function instead, and fix the rule in one place.
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Power Query Custom Functions: Write Once, Call From Any Query in Your Workbook
You've built the same cleanup steps in four different queries. A custom function is how you write them once and call them from all four.
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Star Schema Done Right, Part 3: Slowly Changing Dimensions - The Bit Nobody Explains
A customer moves and changes tier, and some reports should show where they are now while others must show where they were at the sale - the gap is a modelling decision most tutorials skip.
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The Part of Data Modelling Everyone Skips (That Breaks Everything Later)
Your measure is right, your data reconciles, and your year-to-date is still wrong - because the model never had a real date table, only a date column pretending to be one.
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Star Schema Done Right, Part 2: Dimension Tables and Why Cardinality Matters
A dimension table isn't just a lookup. Why fact-to-dimension relationships have to be many-to-one, why bidirectional filtering always causes problems, and how to build dimensions your DAX can trust.
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Build a SharePoint List-Connected Power BI Report (And Handle the 5,000-Row Problem)
Connect Power BI to a SharePoint List the way that doesn't fall over at 5,001 rows - OData filtering at the source, an indexed filter column, and a refresh schedule that doesn't need a gateway.
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Why Most Data Career Advice Is Written for People Who Don't Need It
Learn SQL, build a portfolio, contribute to open source. The canonical data career advice is optimised for getting your first job, and useless immediately after.
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What Actually Changes When You Go From Analyst to Senior Analyst
The title changes, the salary changes, and the list of skills that matter changes completely. Worse, the things that made you good as an analyst quietly start working against you at the senior level.
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Star Schema Done Right, Part 1: What a Fact Table Actually Is (And Isn't)
Most introductions to star schema start with the diagram. The star, the centre, the spokes. This one starts with the question: what problem does a fact table solve that a flat table doesn't? Part 1 builds the intuition before the vocabulary, so the rest of the series makes immediate sense.
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What I Wish Someone Had Told Me About Working With Data in a Small Team
In a small team, you're the analyst, the engineer, the dashboard designer, and the person who explains what a p-value is at the all-hands.
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The Skill Nobody Told You Was Half the Job: Asking Good Questions
The analysts who get traction aren't the fastest at pulling data, they're the best at unpacking what was actually being asked. The skill is asking good questions, and nobody trains for it.
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Build a Power Automate Desktop Flow That Exports a Report and Emails It Daily at 7am
Step-by-step from a blank flow, including how to handle the parts that break the first time.
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Not Everything Should Be Automated — Here's How to Tell the Difference
Automation bias is real: if you can automate something, it feels like you should. But some processes contain judgement calls that automation silently gets wrong, edge cases that require human revie…
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How to Say No to a Data Request Without Burning the Relationship
You can't build every dashboard that gets requested. But 'no' lands differently depending on how you say it — and most data people either say yes to everything and resent it, or say no in ways that…
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Python for Excel Users, Part 2: Grouping, Aggregating, and Replacing Your SUMIFS
SUMIFS and COUNTIFS are great — until your data has 500,000 rows and Excel is grinding. Part 2 shows how to do everything your SUMIFS does, but with pandas groupby — faster, more flexible, and on d…
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Your Power BI Report's Performance Problem Is Probably Your Data Model, Not Your DAX
Slow reports get blamed on complex measures. Complex measures get rewritten. And the report is still slow — because the actual problem is a flat table with 47 columns, many-to-many relationships, a…
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Getting Credit for Work That 'Looks Easy'
The more competent you get, the less people see the effort behind what you deliver. A clean dashboard looks effortless. A fast turnaround looks like it was always fast.
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The Difference Between a Dashboard and a Decision Tool (And Why It Matters)
Most dashboards answer the question 'what happened?' Very few answer 'what should we do?' The gap isn't data — it's intent. A dashboard built for the former often actively gets in the way of the la…
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Why Your Stakeholders Keep Asking for the Wrong Chart
They ask for a pie chart when they need a bar chart. They ask for a table when they need a trend line. This isn't ignorance — it's that they're translating a question into a visual type without kno…
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DAX Context Demystified, Part 4: Iterator Functions and When Row Context Returns
SUMX, AVERAGEX, MAXX — these functions bring row context back into a measure, which sounds helpful until they don't behave the way you expect inside a CALCULATE. Part 4 closes the series with the p…
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When Your Manager Doesn't Understand What You Built
You delivered a clean model, a solid dashboard, a real solution — and got a blank look in the room. The work was right. But explaining technical work to someone who doesn't share your frame of refe…
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DAX Context Demystified, Part 3: Time Intelligence and Why Your YTD Is Probably Wrong
Time intelligence functions look simple - TOTALYTD, SAMEPERIODLASTYEAR — until they aren't. The reason they break isn't the function. It's that context transition interacts with your date table…
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Power Query Is Not the Right Tool for Every Data Problem
Power Query is a brilliant transformation tool. Most of the M code in production is doing things that belong in DAX, SQL, or Python - and the models are slow and the code is unmaintainable.
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Build a 'Latest Record Per Category' Query in Power Query - No Helper Columns
You'll build a reusable Power Query that finds the most recent entry per group - the kind of query that normally tempts people into messy MAXIFS workarounds in Excel. We're doing it properly, wit…
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Avoid Bragging: Talk About Your Work Effectively
Stop cringing. There's a way to talk about your accomplishments in Excel and Power BI that sounds competent, not arrogant. It's all about framing.
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DAX Context Demystified, Part 2: CALCULATE and Context Transition
CALCULATE is the most powerful function in DAX - and the most misunderstood. Once you see how it deliberately replaces the filter context rather than adding to it, every confusing measure result …
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Your Power BI Report Has Too Many Visuals and Not Enough Story
More charts don't mean more insight. Every visual you add is a question your stakeholder has to answer before they understand the point - and most reports ask them to answer fifteen questions bef…
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Build a One-Page Executive Dashboard in Power BI That Stakeholders Actually Open
You'll build a clean single-page report: KPI cards, a trend line, and one slicer. The kind that gets opened voluntarily, not just emailed as a screenshot. Starting from a blank canvas, ending with …
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Nobody Knows What You Actually Do (And That's Partly Your Fault)
You deliver good work consistently, your manager knows you're reliable — and yet somehow you're invisible at promotion time. The problem isn't your output. It's that you've never made your work l…