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Practical Career Skills

Free step-by-step guides to help you learn skills that get you hired and promoted.

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Using AI to Assist Your Excel and SQL Work
All Levels
Data Analysis

Using AI to Assist Your Excel and SQL Work

AI tools can speed up Excel and SQL work, but only if you verify everything. A concrete workflow to generate, test, and trust AI-assisted analysis.

11 min readUpdated Aug 2026
AI-Assisted Python and Pandas: Clean and Analyze Faster
Intermediate
Data Analysis

AI-Assisted Python and Pandas: Clean and Analyze Faster

AI accelerates Pandas work, yet wrong code fails quietly. Use AI to draft, then check every step on real data.

11 min readUpdated Sep 2026
AI-Assisted SQL: Generate, Explain, and Safely Debug Queries
Intermediate
Data Analysis

AI-Assisted SQL: Generate, Explain, and Safely Debug Queries

AI can draft and explain SQL, but you must verify it. A safe workflow for generating, reading, and fixing queries with AI.

11 min readUpdated Sep 2026
AI Data Cleaning: From Messy to Analysis-Ready
Intermediate
Data Analysis

AI Data Cleaning: From Messy to Analysis-Ready

AI turns messy exports into clean tables faster, but needs guardrails. A practical cleanup workflow with checkpoints.

11 min readUpdated Sep 2026
AI-Assisted Data Visualization: Charts and Insights
Intermediate
Data Analysis

AI-Assisted Data Visualization: Charts and Insights

AI suggests charts and spots patterns, yet chart choice is still yours. Use it to prototype, then apply sound design.

10 min readUpdated Sep 2026
How AI Changes the Data Analyst Role
All Levels
Data Analysis

How AI Changes the Data Analyst Role

AI can write the code, so what is left for the analyst? The skills that survive are judgment, problem definition, and verifying AI output. Build them.

11 min readUpdated Aug 2026
The Data Analyst AI Toolbox 2026: Learn vs Skip
All Levels
Career Skills

The Data Analyst AI Toolbox 2026: Learn vs Skip

The 2026 AI toolbox for analysts is noisy. A filter for what actually saves time versus what is hype.

11 min readUpdated Sep 2026
AI Tools for Data Analysis: A Beginner's Workflow
Beginner
Productivity

AI Tools for Data Analysis: A Beginner's Workflow

How to use ChatGPT, Copilot, and Claude for real data work — clean data, write SQL, and build reports. A practical workflow with prompts and guardrails.

10 min readUpdated Aug 2026
Common Interview Questions and Answers
Beginner
Career Skills

Common Interview Questions and Answers

The 12 questions you'll actually be asked, with strong answers you can adapt.

13 min readUpdated Aug 2026
Copilot in Excel: Practical Data Cleaning Workflows
Intermediate
Productivity

Copilot in Excel: Practical Data Cleaning Workflows

What Copilot in Excel actually does well, where it quietly fails, and the prompts that turn messy columns into clean tables and real answers.

12 min readUpdated Sep 2026
How to Write a Cover Letter That Gets You an Interview
All Levels
Career Skills

How to Write a Cover Letter That Gets You an Interview

A cover letter is not a resume summary. Learn the 4-part structure, avoid the mistakes that get letters deleted, and adapt a template to land interviews.

10 min readUpdated Aug 2026
Data Analyst Case Interview: How to Ace the Take-Home Test
Intermediate
Career Skills

Data Analyst Case Interview: How to Ace the Take-Home Test

A data analyst take-home test decides most hires. Learn a repeatable 4-step method to structure, analyze, and present your case before the deadline.

11 min readUpdated Aug 2026
What Does a Data Analyst Actually Do? A Day in the Life
All Levels
Data Analysis

What Does a Data Analyst Actually Do? A Day in the Life

A realistic look at a data analyst day: the meetings, the SQL, the dashboards, and the 80% of the job nobody talks about. Not the marketing version.

11 min readUpdated Aug 2026
The Data Analyst in the AI Era: Career Outlook and Skills
All Levels
Career Skills

The Data Analyst in the AI Era: Career Outlook and Skills

The analyst role is shifting, not vanishing. Where the work moves and which skills keep you employable.

11 min readUpdated Sep 2026
Data Analyst Portfolio Projects That Get You Hired
Intermediate
Career Skills

Data Analyst Portfolio Projects That Get You Hired

Stop guessing what to put in your portfolio. Build 5 real projects recruiters look for, each with a dataset you can download and reproduce.

11 min readUpdated Aug 2026
Remote and Freelance Data Analysis: Find and Deliver Work
All Levels
Career Skills

Remote and Freelance Data Analysis: Find and Deliver Work

Remote and freelance analysis is reachable with the right setup. Where to find work and how to deliver without an office.

11 min readUpdated Sep 2026
Data Analyst Resume: What Recruiters Actually Scan For
Beginner
Career Skills

Data Analyst Resume: What Recruiters Actually Scan For

Recruiters spend 6 seconds on your resume. Here is what they read, what they skip, and 7 fixes that get you past the ATS to the interview pile.

10 min readUpdated Aug 2026
Data Analyst Salary: What to Expect in 2026 (US/UK/CA/AU)
Beginner
Career Skills

Data Analyst Salary: What to Expect in 2026 (US/UK/CA/AU)

Real 2026 data analyst salary ranges by country (US/UK/CA/AU), experience, industry, and city. Glassdoor/Indeed/Levels.fyi data with negotiation tips.

10 min readUpdated Aug 2026
Skills Data Analysts Need in an AI-Heavy Workplace
All Levels
Career Skills

Skills Data Analysts Need in an AI-Heavy Workplace

An AI-heavy workplace changes which analyst skills matter. Keep the fundamentals and add the ones that compound with AI.

11 min readUpdated Sep 2026
How to Prepare for a Data Analyst Take-Home
All Levels
Career Skills

How to Prepare for a Data Analyst Take-Home

A data analyst take-home tests real skill, not trivia. A step-by-step plan to deliver a clean, defensible analysis.

11 min readUpdated Sep 2026
Data Cleaning in Excel
Intermediate
Data Analysis

Data Cleaning in Excel

Remove duplicates, fix formatting, and structure messy data the right way.

12 min readUpdated Aug 2026
Data Cleaning with SQL (Common Mistakes & Fixes)
Intermediate
Data Analysis

Data Cleaning with SQL (Common Mistakes & Fixes)

Clean messy data directly in SQL — find duplicates, fix NULLs, standardize text and dates, and build a repeatable cleaning workflow. Real queries included.

10 min readUpdated Aug 2026
Data Storytelling: How to Present Data So People Act
All Levels
Data Analysis

Data Storytelling: How to Present Data So People Act

Dashboards that get ignored are weak data storytelling. Learn a repeatable 3-part structure to present data, choose the right visual, and drive action.

11 min readUpdated Aug 2026
Excel Advanced Charts: Combo, Waterfall, Profit-Loss
Intermediate
Productivity

Excel Advanced Charts: Combo, Waterfall, Profit-Loss

Build combo, waterfall, and profit-loss charts in Excel. Show variance and running totals the way finance teams expect.

12 min readUpdated Sep 2026
Excel Chart Selection: Line, Bar, Scatter — Which to Use
Beginner
Data Analysis

Excel Chart Selection: Line, Bar, Scatter — Which to Use

Pick the right Excel chart for the data you have: line for trends over time, bar for comparing categories, scatter for relationships. See real examples.

11 min readUpdated Aug 2026
Excel Conditional Formatting: Make Your Data Talk
Beginner
Productivity

Excel Conditional Formatting: Make Your Data Talk

Turn a wall of gray numbers into a report your boss reads in five seconds. Color scales, data bars, icon sets, and formula rules with recipes.

8 min readUpdated Aug 2026
Excel Conditional Formatting Advanced: Rules That Scale
Intermediate
Productivity

Excel Conditional Formatting Advanced: Rules That Scale

Beyond the presets, Excel conditional formatting builds rules that scale. Flag outliers and trends across whole tables.

10 min readUpdated Sep 2026
Excel Date Functions: EDATE, EOMONTH, NETWORKDAYS
Intermediate
Productivity

Excel Date Functions: EDATE, EOMONTH, NETWORKDAYS

Excel EDATE, EOMONTH, and NETWORKDAYS handle month-ends and working days. Build a project timeline and a payroll day count.

10 min readUpdated Sep 2026
Excel Drop-Down Lists & Data Validation: Step by Step
Beginner
Productivity

Excel Drop-Down Lists & Data Validation: Step by Step

Stop typing the same values repeatedly. Build Excel drop-down lists with data validation, create dependent lists, and keep spreadsheets error-free.

9 min readUpdated Aug 2026
Excel Dynamic Arrays Explained: Spill Ranges and #SPILL!
Intermediate
Productivity

Excel Dynamic Arrays Explained: Spill Ranges and #SPILL!

Dynamic arrays changed how Excel formulas work. Understand spill ranges, the #SPILL! error, and implicit intersection with clear examples.

12 min readUpdated Sep 2026
Excel FILTER: Extract Rows by Condition
Beginner
Productivity

Excel FILTER: Extract Rows by Condition

The Excel FILTER function pulls rows that match a condition into a spill range. Learn the syntax with a real sales table you can copy today.

10 min readUpdated Sep 2026
Excel for Data Analysis
Beginner
Data Analysis

Excel for Data Analysis

Turn pivot tables and formulas into a practical analysis workflow that saves you hours.

11 min readUpdated Aug 2026
Excel Formula Errors: Fix #N/A, #VALUE! and #REF!
Beginner
Productivity

Excel Formula Errors: Fix #N/A, #VALUE! and #REF!

Why Excel throws #N/A, #VALUE!, #REF!, #DIV/0! and #NAME?, what each one actually means, and the fastest way to fix it without rebuilding your sheet.

11 min readUpdated Sep 2026
Excel GROUPBY and PIVOTBY: Reports Without PivotTables
Intermediate
Productivity

Excel GROUPBY and PIVOTBY: Reports Without PivotTables

Excel GROUPBY and PIVOTBY build pivot-style reports with formulas. No PivotTable dialog, just live spill ranges.

11 min readUpdated Sep 2026
Excel IF and IFS: Nested Logic Without the Pain
Beginner
Productivity

Excel IF and IFS: Nested Logic Without the Pain

Excel IF and IFS test conditions without unreadable nested stacks. Replace five IFs with one IFS on a grading example.

10 min readUpdated Sep 2026
Excel Data Import: CSV, PDF, and Web into Sheets
Intermediate
Productivity

Excel Data Import: CSV, PDF, and Web into Sheets

Get data into Excel from CSV, PDF, and the web with Power Query. Stop retyping and build refreshable imports.

11 min readUpdated Sep 2026
Excel LAMBDA: Write Your Own Reusable Formulas
Advanced
Productivity

Excel LAMBDA: Write Your Own Reusable Formulas

Excel LAMBDA turns a formula into a named, reusable function. Build a clean margin calculator and stop copy-pasting logic.

12 min readUpdated Sep 2026
Excel Named Ranges: Readable, Robust Formulas
Intermediate
Productivity

Excel Named Ranges: Readable, Robust Formulas

Excel named ranges make formulas readable and resistant to breakage. Name a rates table and watch your model get clearer.

9 min readUpdated Sep 2026
Excel Not Responding or Running Slow: Real Fixes That Work
Intermediate
Productivity

Excel Not Responding or Running Slow: Real Fixes That Work

Excel freezing, hanging, or crawling on large files? These 9 fixes target the actual causes — volatile formulas, bloated ranges, add-ins — not guesswork.

11 min readUpdated Sep 2026
Excel Pivot Tables Advanced: Calculated Fields and Slicers
Intermediate
Productivity

Excel Pivot Tables Advanced: Calculated Fields and Slicers

Go beyond the basics with Excel pivot tables: calculated fields, grouping, and slicers that make reports interactive.

11 min readUpdated Sep 2026
Excel Power Query for Data Transformation: A Practical Guide
Intermediate
Productivity

Excel Power Query for Data Transformation: A Practical Guide

Power Query cleans and reshapes messy data before it ever hits your sheet. Learn to combine, unpivot, and transform data with repeatable steps.

11 min readUpdated Aug 2026
Excel SEQUENCE: Number Series and Date Ranges
Beginner
Productivity

Excel SEQUENCE: Number Series and Date Ranges

Excel SEQUENCE builds number series and date grids with one formula. Build a 12-month calendar and an invoice numbering column.

10 min readUpdated Sep 2026
Excel Shortcuts You Should Know
All Levels
Productivity

Excel Shortcuts You Should Know

50 keyboard shortcuts that save 2+ hours per week. Copy the cheat sheet and start using them on Monday.

9 min readUpdated Aug 2026
Excel SORT and SORTBY: Reorder Data Live
Beginner
Productivity

Excel SORT and SORTBY: Reorder Data Live

Excel SORT and SORTBY reorder ranges live as source data changes. See worked examples with a product list and a by-column sort.

10 min readUpdated Sep 2026
Excel Spill and Dynamic Array Troubleshooting
Intermediate
Productivity

Excel Spill and Dynamic Array Troubleshooting

Dynamic array formulas throw #SPILL! for clear reasons. A troubleshooting path for blocked spills and unexpected outputs.

10 min readUpdated Sep 2026
Excel Tables and Structured References
Beginner
Productivity

Excel Tables and Structured References

Excel Tables turn ranges into smart objects. Use structured references that survive column inserts and auto-expand.

10 min readUpdated Sep 2026
Excel TEXT, TEXTJOIN, and CONCAT: Format and Merge Text
Intermediate
Productivity

Excel TEXT, TEXTJOIN, and CONCAT: Format and Merge Text

Format dates and merge cells with Excel TEXT, TEXTJOIN, and CONCAT. Build clean labels and report headers from raw columns.

11 min readUpdated Sep 2026
Excel UNIQUE: Distinct Values in One Formula
Beginner
Productivity

Excel UNIQUE: Distinct Values in One Formula

Excel UNIQUE returns distinct values from a range in one formula. List categories, customers, or regions without manual de-duplication.

9 min readUpdated Sep 2026
Excel VBA Automation for Beginners: Repetitive Tasks
Intermediate
Productivity

Excel VBA Automation for Beginners: Repetitive Tasks

Write your first Excel macro without being a programmer. Learn the VBA basics, record a macro, and automate the tedious reporting you do weekly.

11 min readUpdated Aug 2026
Excel vs Python: Which Should You Use for Data Analysis?
Intermediate
Data Analysis

Excel vs Python: Which Should You Use for Data Analysis?

Same three analysis jobs done both ways, with real numbers on where Excel wins, where Python wins, and the file sizes where the answer flips.

12 min readUpdated Sep 2026
Excel vs SQL: When to Use Which
Beginner
Data Analysis

Excel vs SQL: When to Use Which

Excel is not a worse SQL and SQL is not a better Excel — they answer different questions. The 3-question test tells you which tool to open.

11 min readUpdated Aug 2026
Excel What-If Analysis: Goal Seek, Data Tables, Scenarios
Intermediate
Productivity

Excel What-If Analysis: Goal Seek, Data Tables, Scenarios

Excel What-If tools reverse-engineer targets. Use Goal Seek, Data Tables, and Scenario Manager on a pricing model.

11 min readUpdated Sep 2026
Excel XLOOKUP: The Modern VLOOKUP Replacement
Intermediate
Productivity

Excel XLOOKUP: The Modern VLOOKUP Replacement

XLOOKUP replaces VLOOKUP and fixes its biggest headaches: it looks left, defaults to exact match, and handles missing values cleanly. See real examples.

10 min readUpdated Aug 2026
Google Sheets ARRAYFORMULA and QUERY
Intermediate
Productivity

Google Sheets ARRAYFORMULA and QUERY

Google Sheets ARRAYFORMULA and QUERY bring Excel-style power to Sheets. Apply formulas to whole columns and pull filtered datasets.

11 min readUpdated Sep 2026
Google Sheets Tips That Will Save You Hours Each Week
Beginner
Productivity

Google Sheets Tips That Will Save You Hours Each Week

Eight Google Sheets tricks that turn a 45-minute repetitive task into a one-minute formula. Conditional formatting, QUERY, IMPORTRANGE, named ranges, and more.

9 min readUpdated Aug 2026
Google Sheets vs Excel
All Levels
Productivity

Google Sheets vs Excel

Which one should you learn first? An honest comparison based on features, jobs, and price.

10 min readUpdated Aug 2026
How to Become a Data Analyst
Beginner
Data Analysis

How to Become a Data Analyst

The skills, portfolio, and job-search strategy to land your first analyst role.

12 min readUpdated Aug 2026
How to Build a Data Analyst Portfolio That Gets Interviews
Beginner
Career Skills

How to Build a Data Analyst Portfolio That Gets Interviews

A hiring manager-skimmed portfolio with 3-5 projects gets more callbacks than a generic resume. See project types, hosting, and review steps.

12 min readUpdated Aug 2026
How to Choose Your Data Tool Stack (Excel/SQL/Python/BI)
Beginner
Data Analysis

How to Choose Your Data Tool Stack (Excel/SQL/Python/BI)

There's no single best stack — there's the right stack for your goal. How to pick from Excel, SQL, Python, and BI tools, mapped to the job you want.

12 min readUpdated Aug 2026
How to Create a Data Dashboard in Excel (Step by Step)
Beginner
Data Analysis

How to Create a Data Dashboard in Excel (Step by Step)

Build a working Excel dashboard in one afternoon — pivot tables, slicers, charts, and KPIs that update themselves. No Excel wizardry required.

10 min readUpdated Aug 2026
How to Learn Data Analysis for Beginners
Beginner
Data Analysis

How to Learn Data Analysis for Beginners

A practical roadmap from Excel fundamentals to SQL queries. Start building real analysis skills in 8 weeks.

10 min readUpdated Aug 2026
How to Read Any Chart: Spotting Misleading Axes and Bad Data
Beginner
Data Analysis

How to Read Any Chart: Spotting Misleading Axes and Bad Data

Most chart mistakes are not about picking the wrong type — they are about truncated axes, cherry-picked ranges, and double axes. Learn to spot all three.

11 min readUpdated Sep 2026
How to Use Pivot Tables
Beginner
Productivity

How to Use Pivot Tables

Summarize thousands of rows in seconds. The definitive pivot table cheat sheet.

11 min readUpdated Aug 2026
How to Use VLOOKUP
Beginner
Productivity

How to Use VLOOKUP

Look up data across tables like a pro — with examples you can copy.

11 min readUpdated Aug 2026
INDEX-MATCH vs XLOOKUP vs VLOOKUP: Which to Use and When
All Levels
Productivity

INDEX-MATCH vs XLOOKUP vs VLOOKUP: Which to Use and When

Three lookup functions, one job. See a side-by-side comparison, the exact cases each wins, and the modern recommendation for 2026.

11 min readUpdated Aug 2026
Is the Google Data Analytics Certificate Worth It in 2026?
All Levels
Career Skills

Is the Google Data Analytics Certificate Worth It in 2026?

The Google Data Analytics Certificate is a low-cost entry point. What it covers, who it helps, and whether employers care in 2026.

12 min readUpdated Sep 2026
How to Optimize Your LinkedIn Profile for Job Search
Beginner
Career Skills

How to Optimize Your LinkedIn Profile for Job Search

Beat recruiter search algorithms and turn profile views into interview callbacks. Headline, About, experience, skills, and settings — what to change and why.

9 min readUpdated Aug 2026
PL-300 Exam Guide: Pass the Power BI Certification
Intermediate
Career Skills

PL-300 Exam Guide: Pass the Power BI Certification

A practical study plan for the PL-300 exam: what is tested, how long it takes, the resources that work, and the mistakes that cost retakes.

12 min readUpdated Sep 2026
Power BI Chart Selection: Pick the Right Visual
Beginner
Data Analysis

Power BI Chart Selection: Pick the Right Visual

Power BI chart selection decides whether a report lands. A quick map from question type to the right visual.

10 min readUpdated Sep 2026
Power BI Copilot: AI Reports, DAX, and Data Prep
Intermediate
Data Analysis

Power BI Copilot: AI Reports, DAX, and Data Prep

Power BI Copilot drafts reports, DAX, and data prep in plain language. What it does well, and where you still steer.

12 min readUpdated Sep 2026
Power BI Data Modeling: Star Schema Basics
Intermediate
Data Analysis

Power BI Data Modeling: Star Schema Basics

Power BI data modeling with a star schema makes reports fast and correct. Build one fact table and clean dimensions.

12 min readUpdated Sep 2026
Power BI DAX CALCULATE and Filter Context
Advanced
Data Analysis

Power BI DAX CALCULATE and Filter Context

Power BI CALCULATE changes filter context to build ratios and YoY. Master it with a month-over-month example.

13 min readUpdated Sep 2026
Power BI DAX: Measures and Calculated Columns
Intermediate
Data Analysis

Power BI DAX: Measures and Calculated Columns

Power BI DAX measures aggregate at query time; calculated columns store per row. Know when to use each with a sales model.

12 min readUpdated Sep 2026
Power BI for Beginners: Build Your First Report
Beginner
Data Analysis

Power BI for Beginners: Build Your First Report

New to Power BI? Connect data, shape it in Power Query, build a sales dashboard with DAX measures, and publish your first report — with a practice file.

12 min readUpdated Aug 2026
Power BI Power Query: ETL from the BI Side
Intermediate
Data Analysis

Power BI Power Query: ETL from the BI Side

Power BI Power Query reshapes data before it loads. Unpivot, merge, and clean steps that refresh on schedule.

11 min readUpdated Sep 2026
Power BI vs Tableau: Which Data Tool Should You Learn First
Beginner
Data Analysis

Power BI vs Tableau: Which Data Tool Should You Learn First

Both Power BI and Tableau are top-tier BI tools. Here is a side-by-side comparison of cost, learning curve, job demand, and which to learn first.

11 min readUpdated Aug 2026
Prompt Engineering for Data Analysts: Reusable Templates
All Levels
Data Analysis

Prompt Engineering for Data Analysts: Reusable Templates

Prompt engineering for analysts is about reproducible asks. Templates that turn vague requests into clean analysis specs.

10 min readUpdated Sep 2026
Python Data Visualization: Matplotlib and Seaborn
Intermediate
Data Analysis

Python Data Visualization: Matplotlib and Seaborn

Python Matplotlib and Seaborn turn DataFrames into charts. Build clean, labeled plots without fighting defaults.

12 min readUpdated Sep 2026
How to Learn Python for Data Analysis (for Excel Users)
Beginner
Data Analysis

How to Learn Python for Data Analysis (for Excel Users)

A practical path from Excel to Python for data work — pandas mapped to the Excel skills you already know. No CS degree, no math prerequisites.

11 min readUpdated Aug 2026
Python for Office Automation: Batch and Repeat Tasks
Intermediate
Data Analysis

Python for Office Automation: Batch and Repeat Tasks

Python automates the office busywork: batch Excel, rename files, email reports. A few scripts that save hours weekly.

11 min readUpdated Sep 2026
Python pandas for Data Cleaning (the Excel User's Guide)
Beginner
Data Analysis

Python pandas for Data Cleaning (the Excel User's Guide)

If you already know Excel, pandas is the next step. Here is how to clean messy data in pandas — with a practice file and real code you can run.

11 min readUpdated Aug 2026
Python Pandas groupby: Aggregate Like SQL
Intermediate
Data Analysis

Python Pandas groupby: Aggregate Like SQL

Python Pandas groupby mirrors SQL GROUP BY. Compute totals by category and reshape results into a report.

11 min readUpdated Sep 2026
Python Pandas: Read, Filter, and Explore DataFrames
Beginner
Data Analysis

Python Pandas: Read, Filter, and Explore DataFrames

Python Pandas reads, filters, and explores tables in a few lines. Load a CSV and answer questions like a SQL query.

11 min readUpdated Sep 2026
Python Regex for Data Cleaning: Patterns That Work
Intermediate
Data Analysis

Python Regex for Data Cleaning: Patterns That Work

Python regex pulls structure from messy strings. Extract IDs, phone numbers, and codes with patterns you can trust.

11 min readUpdated Sep 2026
Python Setup for Data Analysis: Environment and Tools
Beginner
Data Analysis

Python Setup for Data Analysis: Environment and Tools

Set up Python for analysis without breaking your system. Virtual environments, Jupyter, and the packages worth installing.

10 min readUpdated Sep 2026
REGEX in Excel: REGEXTEST, REGEXEXTRACT and REGEXREPLACE
Intermediate
Productivity

REGEX in Excel: REGEXTEST, REGEXEXTRACT and REGEXREPLACE

Excel now has three regex functions. Learn the patterns that solve real cleanup jobs — emails, phone numbers, SKUs — with copy-ready formulas.

12 min readUpdated Sep 2026
Remove Duplicates in Excel: 5 Methods Compared
Beginner
Productivity

Remove Duplicates in Excel: 5 Methods Compared

Five ways to remove duplicates in Excel, from the built-in button to Power Query and a formula check — plus which one keeps your first or last record.

10 min readUpdated Sep 2026
How to Write a Resume That Gets Noticed
Beginner
Career Skills

How to Write a Resume That Gets Noticed

Recruiters spend 6 seconds per resume. Here's exactly what they look for, with 5 templates.

12 min readUpdated Aug 2026
How to Negotiate Your Salary
Beginner
Career Skills

How to Negotiate Your Salary

The exact phrases and strategies to raise your offer — without risking it.

12 min readUpdated Aug 2026
SQL Aggregate Advanced: Conditional SUM, AVG, COUNT
Intermediate
Data Analysis

SQL Aggregate Advanced: Conditional SUM, AVG, COUNT

SQL conditional aggregates compute totals that change with a flag. Use SUM(CASE ...) for pivots inside one query.

11 min readUpdated Sep 2026
How to Write SQL Queries for Business Reports
Intermediate
Data Analysis

How to Write SQL Queries for Business Reports

The exact SQL patterns every analyst rewrites every week — revenue trends, MoM growth, TopN rankings, retention, cohort, and funnel. Copy, adapt, ship.

12 min readUpdated Aug 2026
SQL CASE WHEN: Conditional Logic in Queries
Beginner
Data Analysis

SQL CASE WHEN: Conditional Logic in Queries

SQL CASE WHEN labels rows inside a query. Tag orders as small or large and build status flags without a second table.

10 min readUpdated Sep 2026
SQL Common Errors and How to Debug Them
Beginner
Data Analysis

SQL Common Errors and How to Debug Them

SQL throws vague errors that scare beginners. A debugging checklist for the ten most common query failures.

10 min readUpdated Sep 2026
SQL Date Aggregation: Group by Month, Week, Quarter
Intermediate
Data Analysis

SQL Date Aggregation: Group by Month, Week, Quarter

SQL date aggregation groups sales by month, week, or quarter. Use DATE_TRUNC and date parts on a transactions table.

11 min readUpdated Sep 2026
SQL for Data Analysis: A Beginner's Practical Guide
Beginner
Data Analysis

SQL for Data Analysis: A Beginner's Practical Guide

Learn the SQL basics analysts use every day — SELECT, WHERE, JOIN, GROUP BY — and write your first real business queries in 6 weeks.

8 min readUpdated Aug 2026
SQL GROUP BY and HAVING: Aggregate Correctly
Beginner
Data Analysis

SQL GROUP BY and HAVING: Aggregate Correctly

SQL GROUP BY collapses rows into summary groups; HAVING filters those groups. Learn both with an orders table and common mistakes.

11 min readUpdated Sep 2026
25 SQL Interview Questions (with Practice Queries)
Intermediate
Career Skills

25 SQL Interview Questions (with Practice Queries)

The SQL questions that actually come up in data analyst interviews, with worked queries, what interviewers listen for, and the traps to avoid.

13 min readUpdated Sep 2026
SQL Joins Explained (INNER, LEFT, RIGHT, FULL) with Examples
Beginner
Data Analysis

SQL Joins Explained (INNER, LEFT, RIGHT, FULL) with Examples

Learn SQL joins the way analysts actually use them — INNER, LEFT, RIGHT, and FULL JOIN on real tables with runnable examples and the mistakes to avoid.

10 min readUpdated Aug 2026
SQL or Python First? A Realistic Learning Path for 2026
All Levels
Data Analysis

SQL or Python First? A Realistic Learning Path for 2026

SQL and Python both matter for data work, but which should you learn first? Here is a practical, honest path based on the jobs actually hiring.

11 min readUpdated Aug 2026
SQL Performance and Indexing Basics
Advanced
Data Analysis

SQL Performance and Indexing Basics

SQL indexing stops full table scans on big data. Read EXPLAIN plans and add the right index without guessing.

12 min readUpdated Sep 2026
SQL String Handling: SUBSTRING, REGEXP, CONCAT
Intermediate
Data Analysis

SQL String Handling: SUBSTRING, REGEXP, CONCAT

Clean dirty text in SQL with SUBSTRING, REGEXP, and CONCAT. Split names, strip codes, and standardize categories.

10 min readUpdated Sep 2026
SQL Subqueries vs CTEs: When to Use Which
Intermediate
Data Analysis

SQL Subqueries vs CTEs: When to Use Which

SQL subqueries and CTEs both break problems into steps. Learn when a CTE beats a nested subquery for readability and debugging.

11 min readUpdated Sep 2026
SQL Views and Temporary Tables: Reusable Query Logic
Intermediate
Data Analysis

SQL Views and Temporary Tables: Reusable Query Logic

SQL views and temp tables package query logic for reuse. Know which to reach for in reports versus one-offs.

10 min readUpdated Sep 2026
SQL Window Functions & CTEs (Real Examples)
Intermediate
Data Analysis

SQL Window Functions & CTEs (Real Examples)

Ranking rows, comparing to the previous row, running totals — window functions, made readable with CTEs. A real-world guide on one sample table.

13 min readUpdated Aug 2026
How to Answer Behavioral Interview Questions (STAR Method)
Beginner
Career Skills

How to Answer Behavioral Interview Questions (STAR Method)

The STAR method (Situation, Task, Action, Result) turns vague 'tell me about a time' questions into structured 2-minute answers. See the formula.

10 min readUpdated Aug 2026
Excel SUMIFS and COUNTIFS: Aggregation That Scales
Intermediate
Productivity

Excel SUMIFS and COUNTIFS: Aggregation That Scales

SUMIFS beats SUMIF the moment you need two conditions. Learn the syntax rules, the date traps, and the array tricks that replace helper columns.

11 min readUpdated Sep 2026
Tableau Basics: Your First Dashboard from Scratch
Beginner
Data Analysis

Tableau Basics: Your First Dashboard from Scratch

Build your first Tableau dashboard from scratch. Connect data, drop your first sheets, and ship a one-screen view.

11 min readUpdated Sep 2026
Tableau Desktop Specialist: Exam Guide and Study Plan
Intermediate
Career Skills

Tableau Desktop Specialist: Exam Guide and Study Plan

The Tableau Desktop Specialist cert proves real BI skill. A study plan that covers the exam domains without wasting weeks.

12 min readUpdated Sep 2026
Tableau for Beginners: Build Your First Dashboard
Beginner
Data Analysis

Tableau for Beginners: Build Your First Dashboard

Learn Tableau the fast way — load data, drag to chart, filter with parameters, and publish a clean dashboard. A hands-on beginner path with real examples.

10 min readUpdated Aug 2026
A Data Visualization Portfolio That Gets You Hired
Intermediate
Career Skills

A Data Visualization Portfolio That Gets You Hired

Your charts can land you a job. Build a focused visualization portfolio that shows judgment, not just tool skills, with a process recruiters respect.

11 min readUpdated Aug 2026