Working with Data

ECBS5294 · Central European University · MSBA · 2026–2027

One credit of practical instruction in getting real data into a shape you can trust, and proving the shape is right: grain, keys, types and missing values; SQL on DuckDB for one table and for many; then a small pipeline, from an API’s pages and a statistics office’s file to bronze, silver and gold, with a check at the steps that can lose something; and the habit of reconciling every number before saying what it means.

Instructor: Eduardo Ariño de la Rubia · RubiaE@ceu.edu

Real data arrives messy, and almost none of it crashes. The query runs, the number comes out, and the number is wrong: a join tripled the revenue, a filter quietly dropped every row with a missing value, a total added tonnes to tonnes per person. This course is one credit of practical instruction in getting real data into a shape you can trust, and proving the shape is right. Its thesis is on the first slide and the last: no error is not the same as correct.

Three sessions, one question each: What is this data? · What happens when tables meet? · Can I trust the answer? SQL on DuckDB is the language, and the data is real: a UK online retailer’s half-million invoice lines, a Brazilian marketplace’s orders, the world’s emissions by country, Europe’s municipal waste, and the World Bank’s pages, cached for the room. Every lab hands you a colleague’s report that runs without an error and prints a wrong number. You find out why, write the query the question actually needs, run the check that would have caught it, and explain it to classmates. From Session 2 the labs are done in teams of three, on one laptop, each of you with a role: keyboard, AI, checker.

Before Session 1: the setup check, on the Pre-course setup page. Did not take DS1? Start with the Bridge from DS1.

Schedule

#	Unit	Date	Materials
1	Session 1 — What is this data?	Mon 5 Oct 2026	Released
2	Session 2 — What happens when tables meet?	Mon 12 Oct 2026	Released
3	Session 3 — Can I trust the answer?	Mon 19 Oct 2026	Released

See the Syllabus for assessment, policies, and setup.