SQL: Learning Path
| # | Module | You will be able to |
|---|---|---|
| 1 | Window functions | Use ranking, offset and aggregate windows; choose ROWS vs RANGE; avoid default-frame bugs |
| 2 | Advanced patterns | Recognise and solve gaps & islands, sessionization, funnels, cohorts, intervals, recursion |
| 3 | Performance & dialects | Explain plans, join strategies, skew, and translate between Postgres/Spark/Snowflake/BigQuery |
Then solve the 41 runnable practice problems.