SQL Intermediate Lesson 3: Running Totals and Moving Averages
Running totals, year-to-date by region, 3-month moving averages and share of total with SUM() OVER and window frames (ROWS BETWEEN).
Read article →Coding
Start-to-finish programming for people who work with data: Python, SQL, Java, R, JavaScript, Rust and PowerShell.
SQL Intermediate Lesson 2: Window Functions – ROW_NUMBER, RANK, DENSE_RANK
SQL Intermediate Lesson 2: Window Functions – ROW_NUMBER, RANK, DENSE_RANK
Rank customers, find the top customer in each region and each customer's latest order with ROW_NUMBER, RANK, DENSE_RANK and PARTITION BY.
Read article →SQL Intermediate Lesson 1: Common Table Expressions (WITH)
SQL Intermediate Lesson 1: Common Table Expressions (WITH)
Write readable SQL with CTEs: name a subquery once, chain several steps, compare each customer with the average and compute category shares.
Read article →Java Lesson 6: Collections — List and Map
Java Lesson 6: Collections — List and Map
Store groups of objects with ArrayList and HashMap/TreeMap, loop over them, merge totals by key, and use streams for sums.
Read article →Java Streams for Beginners: filter, map and collect Explained
Java Streams for Beginners: filter, map and collect Explained
Java Streams let you process lists in a clear, declarative style. Learn filter, map, sorted, collect and groupingBy with a small sales example.
Read article →Python for Office Automation: The Complete Starter Guide
Python for Office Automation: The Complete Starter Guide
Use Python to automate everyday office work: set up Python, handle files and folders, read and write Excel, create Word reports, send emails safely,…
Read article →Rename Hundreds of Files at Once with PowerShell
Rename Hundreds of Files at Once with PowerShell
Bulk-rename files on Windows with PowerShell: add dates, replace text, number files and preview every change safely before it happens.
Read article →Python Lists, Dictionaries and Loops for Excel Users
Python Lists, Dictionaries and Loops for Excel Users
The three Python building blocks you use in every script — lists, dictionaries and loops — explained with Excel comparisons and small, runnable examples.
Read article →Data Cleaning With Python pandas: The 15 Fixes You Need for Real Excel Files
Data Cleaning With Python pandas: The 15 Fixes You Need for Real Excel Files
A practical pandas data-cleaning guide for messy Excel exports: header rows, types, dates, duplicates, missing values, text cleanup, splitting columns, mapping, outliers and a…
Read article →Python for Excel Users: Read, Clean and Summarise a Spreadsheet with pandas
Python for Excel Users: Read, Clean and Summarise a Spreadsheet with pandas
A gentle first step from Excel to Python: load a spreadsheet with pandas, clean it, build a pivot table and save the result —…
Read article →Merge 100 Excel Files into One with Python (in 10 Lines)
Merge 100 Excel Files into One with Python (in 10 Lines)
Combine every Excel file in a folder into one sheet with Python and pandas — with a source column, header checks and a summary.
Read article →R Lesson 5: ggplot2 Charts
R Lesson 5: ggplot2 Charts
Make clean charts with ggplot2: the aesthetics-geometry idea, bar and line charts, ordering bars, labels and themes, and saving PNGs for reports.
Read article →