EXIN SQL Foundation case studies
EXIN SQL Foundation · Put your knowledge to work in context.
The EXIN SQL Foundation credential is listed by EXIN, an independent certification and examination institute, as a certification in the SQL domain. This page is an independent study resource for candidates preparing for that exam; it is not affiliated with, endorsed by, or operated by EXIN, and it does not reproduce any official question bank. The EXIN SQL Foundation case studies are 5 cases and about 4,805 words.
1Four Queries, One Wrong Assumption: NULL Semantics in a Shipment Report
Priya is a junior analyst on a three-person data team at a freight-forwarding company. The production database is PostgreSQL 15 and the shipments table holds 480,000 rows.
990 words, about 5 min2Choosing Types and Bolting On Constraints for a 40-Million-Row Invoices Table
Meridian Pay is building an invoices table on PostgreSQL 15 to replace a spreadsheet. The table will hold about 40 million rows over five years.
1,103 words, about 6 min3Autocommit Off, a Missing WHERE, and a Duplicated Load
At a 200-person retailer, a developer is asked to correct missing shipping fees on the orders table, which holds 3.1 million rows and has no primary key - only a non-unique index on order ref . She connects with autocommit disabled and runs UPDATE orders SET ship fee = 0 WHERE ship fee IS NULL; , which reports 412,000 rows affected.
967 words, about 5 min4A Revenue Report Inflated by Join Fan-Out
A marketplace runs MySQL 8.0. Three tables matter: orders (one row per order), order items (an average of 3.4 rows per order) and payments (1.2 rows per order, because some orders are settled in two instalments).
728 words, about 4 min5A View That Refuses Updates, a Slow Lookup and a Gapless Sequence Request
A SaaS company runs PostgreSQL 15 for its billing platform. The reporting schema contains this view: The BI tool uses the view for both reads and simple writes.
1,017 words, about 5 min