Power Query from Scratch, Part 5: Parameters, functions and a model that refreshes itself
A hardcoded folder path and a copy-pasted business rule are the same problem, and parameters plus functions are how you stop editing M code every month.
Excel
// 63 postsTutorials, tips, and deep dives on Excel — every post from bianca.codes tagged Excel.
Excel posts
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A week of actually using Copilot: what a beginner discovers (and what trips them up)
Seven days actually driving Copilot across Excel, Word and PowerPoint - the wins, the confidently wrong deck, and the habit that mattered more than any prompt.
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Power Query from Scratch, Part 4: Custom columns and your first look at M
Three parts of buttons, then a request that needs an 'and' the Conditional Column dialog doesn't have - time to type your first line of M.
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Build a mail-merge report in Word straight from an Excel table
One clean Excel table and a Word template are all it takes for forty personalised reports, once the wizard is driven properly.
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Copilot in Excel: the moment it clicks for a beginner
The first time a plain-English request turns into a real, inspectable Excel formula, the tool stops feeling abstract - and the habit that keeps it honest.
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One Copilot prompt that summarises a 20-tab workbook
The one Copilot prompt that turns twenty unlabelled tabs into a sheet-by-sheet summary, outliers included, in under a minute.
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Power Query from Scratch, Part 3: The transforms that actually matter
Unpivot, split column and group by all look foolproof, right up until the source file adds a column or a name gets typed slightly differently than expected.
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Build a dynamic dashboard with XLOOKUP and one drop-down
One drop-down cell, four XLOOKUP formulas, and every number on the dashboard updates itself - no PivotTable, no slicer, no VBA in sight.
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Learn Python, or learn to drive Copilot? A beginner's honest fork in the road
Two tabs open, four spare hours a week, and everyone insisting the other tab is a waste of your time - here's the no-hype version of the beginner's fork.
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Power Query from Scratch, Part 2: Importing and combining without the copy-paste
Files, folders, and multiple sheets go in three different ways, and the append-versus-merge decision is where most people guess wrong.
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Stop reading Copilot hot takes and just open the thing
Most Copilot opinions come from people who've never clicked into it. Open the thing for an afternoon and form one that's actually yours.
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Build a self-updating summary slide in PowerPoint linked to Excel
Paste Link turns three Excel cells into a PowerPoint object that updates itself, once you stop letting the linked range look like a spreadsheet.
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LAMBDA: the day Excel let you write your own functions
Copy-pasting the same formula across a workbook used to be the only way to reuse logic - until LAMBDA let you name it and call it like any other Excel function.
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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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The F4 trick that locks cell references in one keystroke
Stop typing dollar signs by hand - one keystroke cycles through every Excel cell reference mode instantly.
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Power Query from Scratch, Part 1: The mental model nobody teaches you
Most people learn Power Query by clicking through wizards. Nobody explains what it's actually doing - and that gap is why queries break in confusing ways.
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Your nested IF statements are technical debt
A formula with six nested IFs works fine, right up until the rule changes and you're reverse-engineering a 300-character one-liner you wrote six months ago.
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Build a Monthly Report Card in a Single Python in Excel Cell
Python in Excel can't write a file, but it can turn a transaction table into a chart that lives in the workbook and never goes stale - in one =PY() cell.
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Python in Excel: When a Cell Stops Being a Number and Becomes a DataFrame
For forty years an Excel cell could hold one of four things, and Python in Excel quietly added a fifth: a whole pandas DataFrame, living inside a single cell.
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The Hardest Part of Working With Messy Data Isn't the Cleaning - It's Knowing When to Stop
The mechanics of cleaning data are the straightforward part. The hard part has no function and no checklist: deciding which imperfections actually matter, and stopping there.
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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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Pivot Tables Are Still Great - But GROUPBY Is What You Should Be Using for New Work
Pivot tables aren't obsolete, but reaching for one by reflex on every new analysis is a quiet tax GROUPBY does not charge.
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Build a Self-Updating Sales Summary Using GROUPBY - From Raw Transaction Data
A raw transaction table becomes a monthly sales summary by category with one GROUPBY formula - no PivotTable, no Refresh, and it updates the moment you add a row.
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GROUPBY: Excel's Answer to Pandas groupby - Without a Pivot Table in Sight
A pivot table is a tool you operate. GROUPBY is the same group-and-aggregate logic as a single spilled formula - the summary recalculates itself, with no fields to drag and nothing to refresh.
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3-Minute Win: Replace Your Most-Used Pivot Table With a Single GROUPBY Formula
A pivot table is a snapshot that needs refreshing. GROUPBY is a formula that recalculates itself. Swapping one for the other takes about 90 seconds and removes a recurring chore.
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REDUCE: How to Build Running Calculations Across Any Dimension in Excel
REDUCE is the most powerful of the functional array functions and the most overlooked. The lambda which means you can accumulate strings, and replace calculations that used to need VBA.
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3-Minute Win: Use REDUCE to Concatenate a Column of Values Into One Cell
Joining a column of names or tags into one comma-separated string used to need TEXTJOIN or a helper column. REDUCE does it in one formula, and lets you transform each item before it gets concatenated.
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Excel Is Quietly Becoming a Programming Language and Most Users Haven't Noticed
LAMBDA, MAP, REDUCE, SCAN, BYROW. These are functional programming primitives. Excel is shipping them one by one, and most users are still writing nested IFs. The spreadsheet you learned in 2015 has been quietly replaced by something much more powerful.
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Build a Dynamic Data Validation List That Updates Itself When Your Source Table Grows
You'll build a dropdown list that reads from a structured table and includes every new row automatically. No named range maintenance, no 'why isn't my new entry showing up' moments.
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MAP: Apply Any Transformation to Every Element in an Array - Without a Loop
MAP takes your LAMBDA and runs it on every element in an array. No helper columns, no dragging formulas, no VBA loops.
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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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Build a Dynamic Summary Table Using BYROW and LAMBDA — No Pivot Table Required
You'll build a summary that calculates a custom metric for every row in your dataset without a pivot table, without helper columns, and without copying formulas down. BYROW plus a LAMBDA gives you …
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BYROW and BYCOL: Apply Any Formula to Every Row or Column, Automatically
BYROW hands your function an entire row at a time. BYCOL does the same by column. Together they replace an entire category of 'drag this formula down and keep it updated' work — and when you combin…
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The Excel Functions Your Spreadsheet Has Been Missing for Ten Years
XLOOKUP, LET, LAMBDA, BYROW, SCAN, MAP — Microsoft shipped more genuinely useful functions in the last three years than in the previous decade. If you learned Excel before 2022 and haven't revisite…
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3-Minute Win: Use BYROW to Apply a Formula to Every Row Without Dragging It Down
BYROW hands your function an entire row at a time — which means 'apply this logic to every row in this range' is one formula in one cell. No dragging, no CTRL+SHIFT+ENTER, no missing the last row w…
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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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Stop Using Helper Columns for Running Totals — There's a Better Way
Helper columns aren't wrong. But when a running total requires three of them and breaks every time someone inserts a row, you've created fragility in exchange for familiarity. The Excel array funct…
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Build a Rolling 12-Month Balance Tracker That Updates Without Touching a Formula
You'll build a balance tracker using SCAN and a structured table that extends itself as new rows come in. No helper columns, no fragile cell references, no 'just re-paste the formula down.' Add a r…
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SCAN: The Excel Function That Keeps a Running Total of Anything
Running totals used to mean helper columns or array gymnastics. SCAN changes that — it applies a function cumulatively across an array and hands you back every intermediate result. Once you see it …
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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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3-Minute Win: Use SCAN to Add a Running Total Column Without Any Helper Columns
SCAN hands you every intermediate result as it accumulates — which means a running total is one formula that spills down the column. No helper rows, no dragging, no breaking when someone inserts a …
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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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Excel Formulas Are Getting Too Complex - And LAMBDA Is Why That's Actually Fine Now
The counter-argument to 'if your formula needs a scrollbar to read, it's wrong.' With LAMBDA, complexity lives in one named place and gets called cleanly everywhere else. The formula in your cell c…
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Build a Reusable OVERDUE LAMBDA and Use It in Three Different Tables
You'll build a named LAMBDA called OVERDUE that takes a date and a threshold and returns a clean status label. Then you'll call it in three different tables in the same workbook. By the end, you'll…
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LAMBDA: How to Write the Excel Functions Microsoft Didn't
Before LAMBDA, every Excel function that existed was one Microsoft decided to write. After LAMBDA, you can write them yourself — naming the logic, hiding the complexity, and calling your custom fun…
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3-Minute Win: Name Your LAMBDA Function and Call It From Any Cell in the Workbook
One function definition in the Name Manager, and every cell in the workbook can call it like a built-in. LAMBDA + named functions means you stop copy-pasting logic and start writing like someone wh…
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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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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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LET: How to Write Excel Formulas That You Can Actually Read Tomorrow
Complex formulas aren't the problem. Unreadable ones are. Before LET, you had to repeat the same range reference six times or accept that your formula was a black box. LET gives you named variables in
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Why 'Just Learn SQL' Is the Wrong Advice for Most Excel Users
The advice is everywhere: if you're serious about data, you need SQL. But for most analysts already working in Excel and Power BI, the gap isn't SQL knowledge - it's data modelling instinct. Here…
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3-Minute Win: Name Your Intermediate Formula Steps With LET
One tweak to your most-used formula and it suddenly reads like plain English. LET() lets you name the messy middle parts — so next month's you won't need to reverse-engineer what current you was …
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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…
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VLOOKUP Isn't Broken - You're Just Refusing to Move On
It works, so why change it? Because every workaround you've added to compensate for VLOOKUP's limits is technical debt in your spreadsheet - and it compounds. The cost isn't visible until somethi…
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Build a Drop-In XLOOKUP Upgrade for Every VLOOKUP in Your Workbook
Stop replacing VLOOKUPs. Your workbook deserves XLOOKUP without touching the formula.
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Dynamic arrays: FILTER, SORT, UNIQUE - what changed
I spent years writing 400-character Ctrl+Shift+Enter arrays just to filter a table, but the calculation engine finally changed the rules and killed that misery for good.
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The state of email merge in 2026
It is 2026, and we are still stringing together premium Power Automate connectors just to avoid the Word mail merge wizard.