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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

SQL Fundamentals

Databases, tables, keys and the anatomy of a query.

How relational databases work

✓How relational databases work — tables, keys and typesBefore writing SQL, understand what a database is, how tables relate through primary and foreign keys, and why data types matter.Beginner35 min

Selecting and filtering rows

✓SELECT, WHERE and sorting — your first real queriesRetrieve exactly the rows and columns you need, filter with conditions, sort results, remove duplicates and limit output.Beginner50 min

Aggregation and Logic

Summaries, grouping, NULLs and conditional logic.

Aggregating data

✓Aggregations, GROUP BY and HAVINGSummarise thousands of rows into business metrics, break them down by dimension, and filter groups.Beginner50 min

NULL and CASE

✓NULL and CASE WHEN — missing values and conditional logicHandle missing values correctly and build business categories and conditional calculations with CASE WHEN.Beginner40 min