Week 3, Data Sources: AR, Aging, and Cash Application

Build the AR aging report twice on the same 20,015 invoices. Excel first, then SQL. Sep 7–13.

This week

• Lecture 3, Data Sources: AR, Aging, and Cash Application
  The full lecture deck, with a self-check on most slides and the Ask AI tutor built in. Open it before the Wednesday session or work through it afterwards.
• Lab 3, Summit Gear AR, from tables to aging report
  Five parts, all in Excel. Fill the analytical columns on 20,015 invoices, build the aging pivot, hunt the discrepancies, and hand in one workbook. 100 points, due Sunday, September 13.
• SQL Workbench, Summit Gear AR
  The in-browser SQL editor where Homework 3 happens. The full Summit Gear database loads client-side, and the eight homework prompts sit in the sidebar. Nothing to install.

Trainers, walk these first

• SQL Fundamentals trainer
  SELECT, FROM, WHERE, ORDER BY, LIMIT. Twelve short lessons against a real database. Start here if SQL is new to you.
• JOIN trainer
  INNER against LEFT, the Venn diagram, the XLOOKUP parallel, and the 1:n trap that quietly doubles a SUM. Walk this before the Aggregate trainer.
• Aggregate trainer
  GROUP BY, SUM, COUNT, AVG, HAVING, with an animated row-to-summary collapse so you can see what an aggregate actually does to the rows.
• Aging builder
  The headline trainer. Builds the AR aging query one piece at a time and lands exactly the query you recreate in Homework 3.
• Excel concepts trainer
  The eight Excel moves Lab 3 assumes: SUMIFS at 20K rows, single and chained XLOOKUP, IFS for aging buckets, the one-cell cutoff parameter, and pivots. Each lesson pairs the formula with a Copilot prompt.

Reference

• Left Join Visualizer
  Six lockbox payments, two of them pointing at invoices that are not in the system. Watch an INNER JOIN drop them without raising an error, then watch a LEFT JOIN surface them.
• SQLite cheat sheet
  One page covering every piece of syntax this week uses. Keep it open in a tab while you write the homework queries.