Oracle

Oracle supports JdbcTemplate, annotation/XML Mapper, Lambda, BaseMapper, object mapping and JDBC transactions. Handwritten SQL retains Oracle semantics. Builders generate SQL through the Oracle dialect, but not every general interface applies.

API Support and Boundaries

Capability	Boundary
CRUD and pagination	Supported; builder pagination generates nested ROWNUM queries, with slicing performed by the database
Entity and Map mapping	Supported; unquoted column names commonly return uppercase, so do not assume raw Map keys are lowercase
Strings	Oracle treats empty character strings as NULL; empty strings and null need not round-trip distinctly
Generated keys	Auto uses generated keys; Sequence with @KeySeq obtains the value before insertion
Batch inserts	Lambda/BaseMapper use individual execution, including inserts without key backfill; this does not mean Oracle JDBC lacks batching
Transactions	Supports commit and rollback; isolation levels and savepoint release depend on Oracle JDBC, so not every database transaction option is portable
Arrays, cursors and specialized types	Use the corresponding Oracle JDBC registration, retrieval, and type-handling conventions

Quick Overview of Differences

Concern	Oracle Behavior
Primary Key Generation	IDENTITY (12c+) or sequence
Pagination	ROWNUM nested query
Write Conflicts	MERGE INTO ... WHEN MATCHED ... WHEN NOT MATCHED ...
Batch Writes	Lambda/BaseMapper inserts execute individually; native JDBC Batch is a separate call path
Stored Procedures	Supported
Sequences	Supports seq.NEXTVAL

Key Generation

Oracle 12c+ IDENTITY columns are backfilled via JDBC generated keys. Critical configuration: keyColumn must be explicitly specified, otherwise the Oracle JDBC driver only returns ROWID instead of the business primary key column.

Mapper files can use selectKey to obtain a sequence value before INSERT:

<insert id="insertUser">
    <selectKey keyProperty="id" keyColumn="id" order="BEFORE">
        SELECT user_info_seq.NEXTVAL AS id FROM dual
    </selectKey>
    INSERT INTO user_info (id, name, age) VALUES (#{id}, #{name}, #{age})
</insert>

The Builder API supports KeyType.Sequence + @KeySeq for automatic sequence assignment. See Key Generation.

Special Topics

• Programmatic API: queries, writes, multiple results, and stored routine differences.
• Mapper API: annotations, Mapper reads and writes, and execution differences.
• Builder API: Supported operations, datasource-specific behavior, and usage.
• Pagination: Pagination principles, usage and notes.
• Insert Conflicts: Conflict scenarios, strategies, usage and notes.
• Key Generation: IDENTITY, sequences, keyColumn, and selectKey.
• Data Backfill: return inserted, updated, or deleted field values with RETURNING INTO.
• Parameters and rules: empty strings and parameter reuse.
• Type Support: Java values, storage choices and readback boundaries.
• Transaction Support: handling partial failures with transactions.

Related Documentation

For common usage, see Core API.