Micronaut JDBC — programmatic SQL

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; 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 proceeding
• VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
• BEFORE APPLYING: Read the reference for detailed rules and examples

When to use this skill

• Review JDBC or SQL data access in a Micronaut project
• Improve transactions and parameter binding for Micronaut JDBC
• Translate SQLException to domain exceptions or stream large result sets
• Fix self-invocation bypassing @Transactional in Micronaut
• Review Hikari or pooled datasource usage in Micronaut JDBC

Workflow