// office guides

FormulAI guides

Short, practical articles to understand what the AI writes for you — and to fix a formula when your file doesn't behave as expected.

SQL JOINs Explained with Real Examples (INNER, LEFT, RIGHT, FULL)

A practical walkthrough of every SQL JOIN type using a small customers/orders dataset, with the mistakes that silently duplicate or drop rows.

Encoding errors, mixed date formats, duplicated rows and numbers stored as text: a reproducible Pandas cleaning script you can adapt to any export.

Exact match, approximate match, two-way lookups, last occurrence and multiple return columns: everything XLOOKUP can do, with ready-to-copy formulas.

ROW_NUMBER, RANK, SUM OVER and LAG explained on a sales table, with the business questions each one answers.

Merge several Excel files, build a summary table, format it and save a ready-to-send report — a 40-line script that replaces an hour of copy-paste.

QUERY, IMPORTRANGE, ARRAYFORMULA, FILTER, UNIQUE, SPLIT, REGEXEXTRACT and more — with the everyday task each one solves.

VLOOKUP remains the most taught formula, but INDEX/MATCH beats it on robustness. A concrete comparison using a billing file.

Total revenue by month, salesperson, and status using a single, readable, and fillable formula.

Why your query returns an aggregation error, and how to correctly filter a grouped result.

Stray spaces, duplicates, and wrong date formats: the minimal script to fix a customer export.

The three functions that replace half of your Pivot Tables in Excel 365 and Google Sheets.