511-frameworks-micronaut-jdbc

# Micronaut JDBC — programmatic SQL Apply programmatic JDBC patterns in Micronaut with safe SQL and clear transactions. **What is covered in this Skill?** - Injected javax.sql.DataSource (Hikari-backed with micronaut-jdbc-hikari) and try-with-resources for Connection / PreparedStatement - PreparedStatement with bind parameters — never string concatenation - Mapping ResultSet rows to Java records (dedicated mapRow method) - Safe single-row queries with Optional<T>; never assume rs.next() succeeds - SQLException translation to domain exceptions (catch-translate-rethrow) - Streaming large result sets with setFetchSize to avoid OOM - Batch updates with addBatch / executeBatch for bulk inserts - @Transactional service boundaries and TransactionDefinition.Propagation (e.g. REQUIRES_NEW for independent commits) - Self-invocation pitfall: call transactional collaborators through injected beans, not this.method() - SQL text blocks for multi-line SQL (upserts, dialect-specific clauses) - When to prefer Micronaut Data (`@512`) vs raw JDBC **Scope:** Apply recommendations based on the reference rules and good/bad code examples. ## Constraints Compile before JDBC refactors; verify after changes. - **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change - **PREREQUISITE**: Project must compile before applying JDBC improvements - **SAFETY**: If compilation fails, stop immediately - **BLOCKING CONDITION**: Compilation errors must be resolved by the user before ...