Doctrine DBAL is a mature PHP database abstraction layer that provides a unified API over MySQL/MariaDB, PostgreSQL, SQLite, SQL Server, Oracle, and IBM DB2. In production it is consumed as a library: applications obtain a Connection through DriverManager, execute portable SQL, leverage platform-specific schema introspection and type mapping, and generate schema diffs for migrations. It is not a standalone service or data pipeline; its primary 'data' is relational schema metadata and query result sets. Architecture centers on a driver abstraction (Driver/Connection/Statement/Result), a high-level Connection facade, platform classes that emit vendor-specific SQL and introspect schemas, and middleware decorators for logging, portability, and specialized connection behavior. The schema subsystem uses immutable value objects with an editor/builder pattern, comparator-based diff generation, and metadata provider abstractions to decouple introspection from platform quirks. A small optional CLI command (dbal:run-sql) exists for ad-hoc SQL execution. Maintenance is active: the codebase targets current PHP (^8.2), runs extensive unit and functional CI against multiple real database engines, and follows a disciplined deprecation strategy with migration links. Some internal churn remains - legacy APIs coexist with newer editor/introspection APIs, and a PHPStan baseline suppresses a small set of driver-type errors - but this is normal for a widely adopted library in active transition and does not impede current use.