Tier 1 · Gated foundation
Foundations of Databases with SQL
Fluent SQL and competent relational modelling — the data floor every WIATech diploma assumes.
- Duration
- 6 weeks
- Tier
- Tier 1 · Foundations
- Certificate
- WIATech Certificate in Foundations of Databases with SQL
A six-week intensive that builds genuine SQL fluency and sound relational design judgement. Students learn to read a business problem, design the small-to-medium schema that supports it, and answer questions about the data in SQL — including the JOIN-heavy queries that separate someone who can use SQL from someone who has only seen it. Fluency is built through volume, with real Sierra Leone datasets such as mobile money transactions, school enrolment records and WAEC results.
§ What you'll be able to do
- Write fluent SQL against any small-to-medium schema, including multi-table JOINs and aggregation
- Read SQL written by others and predict what it returns
- Design a 5–15 table schema from a business description, with appropriate keys and constraints
- Diagnose common bugs such as Cartesian products, NULL handling and GROUP BY errors
- Refactor messy SQL into clean, readable queries another engineer can maintain
- Hold a coherent conversation about a database design and defend the choices
§ What you'll cover
What Relational Data Is
The relational model, why it has dominated for fifty years, spreadsheets versus databases, PostgreSQL as the working tool, and the SQL language family.
Fluent SQL — Reading and Writing Data
The largest module: CRUD, filtering and sorting, the operator vocabulary, aggregation, grouping, conditional logic and NULL handling, built through high query volume.
JOINs and Multi-Table Querying
The leap from one table to many — the JOIN family, the ON clause, multi-table and self joins, simple subqueries, set operations, and how JOINs go wrong.
Designing the Schema
Turning a business description into a small-to-medium schema: entities, keys, cardinalities and junction tables, constraints, data types, and light-touch normalisation.
Putting It Together
The integration layer — querying, JOINing and designing wired into one end-to-end capability, plus realistic data, reading others' SQL, refactoring and schema handoff.
Capstone
The Working Schema
Choosing one of three Sierra Leone business scenarios, the student delivers a complete PostgreSQL schema, an ER diagram, a query suite, and an oral defence of the design.
§ Tools you'll use
- PostgreSQL
- psql
- DBeaver or pgAdmin
- dbdiagram.io or draw.io
- A text editor for SQL files
§ Where it leads
A gated foundation that four of the six diplomas assume from Semester 01 — SWE 200 opens at PostgreSQL production depth, AIE 300 builds advanced SQL and data engineering on it, DAT 200 takes SQL fluency to analytical mastery, and CLD 200 frames managed databases on a relational grounding.