SQL joins: a small reference with predictable results
Use a tiny customer-and-order dataset to see inner joins, left joins, and the filter placement that changes their meaning.
A relational database used for web applications and transactional workloads.
Official documentationA relational database used for web applications and transactional workloads.
This profile covers a database in the Relational databases category.
Start with your access patterns, data size, concurrency, and recovery requirements. Check the official documentation for the exact edition, engine version, and deployment model you intend to use.
For self-managed deployments, account for upgrades, monitoring, access controls, and the process for recovering your data.
Related guides appear below as they complete editorial review. Use those examples as a starting point for testing a representative development workload.
Use a tiny customer-and-order dataset to see inner joins, left joins, and the filter placement that changes their meaning.
Understand why checking out a shopping basket and analyzing a year of sales ask very different things of a database.
Separate atomicity from isolation and learn why two individually correct transactions can still surprise each other.
Calculate a running total and rank orders within each customer without collapsing the underlying rows.
Build an index around a real access pattern, then use EXPLAIN to understand what it helps—and what it doesn't.