05/ 11·6 lessons·2 h 25 min

Querying across tables

Tying data together: joins (inner/left/right/full), self-joins, aggregation with GROUP BY/HAVING, DISTINCT ON (the latest order per customer), EXISTS vs IN subqueries, and CTEs with materialization. This is where data turns into answers to business questions.

Start module→Continue · JOIN: inner/left/right/full→Reread module→Next module →
/ lessons

Lessons

6 lessons · 2 h 25 min
  1. 01JOIN: inner/left/right/full↳ continue from here#join#inner#left25m
  2. 02Multi-table and self-joins↳ continue from here#join#multi-table#self-join25m
  3. 03Aggregation: GROUP BY/HAVING↳ continue from here#aggregation#group-by#having25m
  4. 04DISTINCT ON↳ continue from here#distinct-on#order-by#top-n20m
  5. 05Subqueries: EXISTS vs IN↳ continue from here#subquery#exists#in25m
  6. 06CTEs and materialization↳ continue from here#cte#with#materialized25m