Data and AI

Advanced SQL and Query Optimisation

Go beyond analyst-level SQL into the query patterns and performance discipline real data engineering work demands

16h4 lessonsTier 2 hireabilityTier 2 certificate

What you'll be able to do

You can write advanced SQL (recursive CTEs, complex window functions, set operations) confidently, read and act on a query execution plan, and apply genuine indexing and optimisation judgement to slow-running queries.

Job titles this qualifies you for

Data EngineerAnalytics EngineerETL Developer
Market intelligence
Demand
High
Remote
72% remote roles
Nigeria salary
Not a primary local hiring category
Remote (USD)
$114,500–$137,500/year for the typical remote mid-level range (25th-75th percentile); average around $130,000-$148,000/year; senior remote data engineers average $191,822/year

Lessons

Stage 1 — Foundation
1
Recursive CTEs and Set Operations
40 min
2
Advanced Window Functions for Engineering Tasks
40 min
Stage 2 — Applied
1
Reading and Understanding Query Execution Plans
40 min
2
Indexing Strategy and Practical Optimisation
40 min
Tier 2 Proof Submission

Advanced SQL and Query Optimisation Portfolio

Demonstrate genuine competence with recursive CTEs, advanced window functions, execution plan reading, and indexing strategy.

1.A recursive CTE for a hierarchical employee-manager query
2.A ROW_NUMBER()-based deduplication query and a LAG-based days-since-last-order explanation
3.An execution plan diagnosis and a proposed fix for a slow hypothetical query
4.A composite index design with a column-order explanation
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