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Module 2

SQL

Retrieve, combine and summarise data in relational databases — from first SELECT to window functions and query performance.

Difficulty:All beginner intermediate advanced expert

Advanced Analytical SQL

Window functions and business query patterns.

Window functions

✓Window functions — ranking, LAG/LEAD, running totals and moving averagesCompute values across related rows without collapsing them — the most powerful analytical feature of SQL.Advanced70 min

Business query patterns

✓Business query patterns — period comparisons, customer-level analysis and cohortsThe queries analysts write every week — YoY and MTD comparisons, customer-level metrics, and cohort retention tables.Advanced70 min

Performance and Data Quality

Indexes, execution plans, validation and reconciliation.

Query performance

✓Query performance — indexes, execution plans and common problemsWhy some queries take milliseconds and others minutes, how indexes work, how to read an execution plan, and the habits that keep analytical SQL fast.Advanced45 min