SQL
Realistic Scenarios: Analysis and Optimisation
Six end to end problems of the kind real work produces - a sales report, a retention table, a data quality audit, a duplicate cleanup and two optimisa...
#Practice
Exercises and worked practice problems.
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SQL
Advanced Practice: Subqueries, CTEs and Window Functions
Twelve harder exercises - correlated subqueries, recursive CTEs, ranking, running totals and top N per group - with solutions and the reasoning behind...
SQL
Intermediate Practice: Joins and Aggregation
Fifteen exercises combining joins, grouping and having, each with the solution and a note on the trap it was designed to expose.
SQL
Beginner Practice Queries
Twenty graded exercises on SELECT, filtering, sorting and simple functions, each with a worked solution and the reason it is written that way.
SQL
The Sample Database Used in This Path
Two small schemas - a company HR database and a shop sales database - used by every example in this SQL path. Create them once and follow along.