# PostgreSQL

> Selected Engineer ApS work demonstrating PostgreSQL — the achievements that prove it.

- [Directed full‑stack GIS map development, overseeing PostgreSQL, Mapbox, ReactJS, and NodeJS to deliver an integrated solution.](https://advisory.engineer.company/portfolio/directed-full-stack-gis-map-development-overseeing-postgresql-25/)
- [Led the development, deployment, and support of over 30 GIS projects, demonstrating expertise in PostgreSQL, Bash, Python, JavaScript, GDAL, ArcGIS, PostGIS, and Mapbox technologies.](https://advisory.engineer.company/portfolio/led-the-development-deployment-and-support-of-over-35/)
- [Built a layered automated test suite — 981 Go tests, 543 frontend and browser specs, 494 SQL behavioural tests — with mutation testing, property‑based tests and an accessibility gate.](https://advisory.engineer.company/portfolio/built-a-layered-automated-test-suite-across-four-layers-94/)
- [Built the payments and entitlements layer — Stripe alongside Apple and Google in‑app purchase — gating the directory, search and export through an 11‑table access model checked on the server.](https://advisory.engineer.company/portfolio/built-the-payments-and-entitlements-layer-96/)
- [Built the loyalty and reputation system — 67 functions over a 31‑table ledger, with leagues, badges and a redemption shop — taking a row lock on the balance to close the double‑spend window.](https://advisory.engineer.company/portfolio/built-the-loyalty-and-reputation-system-105/)
- [Built the hiring marketplace and the seafarer career workspace — 151 stored functions across 48 tables — covering vacancies, applications, certificates, rank progression and verified sea time.](https://advisory.engineer.company/portfolio/built-the-hiring-marketplace-and-career-workspace-107/)

<https://advisory.engineer.company/categories/postgresql/>