Practical walkthroughs for working with CSV and Excel files as data rather than as documents — written against DuckDB running in the browser, so every example is runnable without a database or an upload.
Run real SQL against a CSV file without importing it into a database. A practical walkthrough using DuckDB in the browser, with worked SELECT, GROUP BY, and JOIN examples.
Excel stops at 1,048,576 rows and slows down long before that. Practical ways to open, inspect, and query multi-hundred-megabyte CSV files, including a browser-based option with no upload.
Query .xlsx workbooks with SQL instead of nested formulas. How sheets map to tables, how to handle messy headers and merged cells, and how to join a spreadsheet to a CSV.
Online CSV and SQL tools require handing over your file. How browser-based analysis with WebAssembly avoids that, what "local" actually means technically, and how to verify the claim yourself.
Find added, removed, and modified rows between two versions of a CSV export. A SQL approach using a key column, plus how to handle rows that changed in only one field.
Seven SQL checks that catch the errors which quietly corrupt analysis: duplicate keys, wrong types, hidden nulls, impossible ranges, inconsistent categories, and truncated exports.
Turn a JSON export into a queryable table and run SQL against it. How array, wrapper, and nested shapes map onto rows and columns, and what to do with nested objects.