What to know before you read.
- A strong SQL project demonstrates data modelling and validation, not only query syntax.
- Every result should have an explicit grain and a business question.
- Include constraints, tests and query-performance reasoning for stronger evidence.
Choose a connected domain
Use enrolments, bookings, commerce, support or inventory where entities and relationships are visible. Write ten questions the database must answer before creating tables. Those access needs keep the schema connected to use rather than becoming a diagram exercise.
Design and constrain the schema
Identify entities, primary keys, foreign keys, required fields and valid ranges. Normalise repeated concepts, then denormalise only with a documented reason. Add constraints so invalid states are rejected near the data boundary.
Load and verify data
Create or import permitted sample data with enough variation for meaningful joins and aggregation. Check row counts, uniqueness, missingness and relationship coverage. Record every cleaning transformation.
Answer layered questions
Begin with filters and grouping, then add multi-table joins, subqueries, common table expressions and window functions. State the intended row grain above each query and reconcile totals against a simpler calculation.
- Operational lookup
- Management summary
- Trend over time
- Segment comparison
- Data-quality check
- Ranking or running total
Explain performance and decisions
Add appropriate indexes to selected queries and compare the execution plan before and after. Document trade-offs and package the schema, setup, queries and findings. The SQL & Databases Certificate of Specialisation provides the complete 30-hour foundation for this case study.
Questions readers often ask.
What is a good SQL beginner project?+
A booking, inventory or enrolment database offers clear relationships and useful analytical questions.
Should a SQL project include a dashboard?+
It can, but the schema, validated queries and reasoning should remain understandable without the dashboard.
How can I show SQL performance knowledge?+
Use indexes on selected access patterns and compare query plans while explaining write and storage trade-offs.
