Insert Conflicts

Conflict handling decides whether an insert matching an existing row should fail, be ignored, or update that row. Typical scenarios include replayed jobs, data synchronization, repeated imports, and insert-or-update operations. It is an INSERT execution strategy, not a separate ordinary UPDATE.

Strategies

Strategy	DB2 statement	Result
Into	INSERT INTO ... VALUES (...)	The database reports a conflict
Ignore	MERGE ... WHEN NOT MATCHED THEN INSERT	Matched rows remain unchanged; unmatched rows are inserted
Update	MERGE ... WHEN MATCHED THEN UPDATE ... WHEN NOT MATCHED THEN INSERT	Matched rows are updated; unmatched rows are inserted

Ignore and Update use mapped primary-key columns for the MERGE match. DB2 performs both matching and writing.

Usage

Assume UserInfo maps to this table, with id marked as the entity primary key. Alice already exists:

CREATE TABLE user_info (
    id INTEGER NOT NULL PRIMARY KEY,
    name VARCHAR(64),
    age INTEGER
);
INSERT INTO user_info (id, name, age) VALUES (1001, 'Alice', 18);

Submit the same ID with a new name:

UserInfo user = new UserInfo();
user.setId(1001);
user.setName("Bob");
user.setAge(20);

int rows = lambda.insert(UserInfo.class)
        .onDuplicateStrategy(DuplicateKeyStrategy.Update)
        .applyEntity(user)
        .executeSumResult();

With Update, row 1001 becomes Bob, age 20. With Ignore, Alice remains unchanged. Default Into reports the duplicate key.

Use Ignore to skip matched rows. Omitting the strategy or selecting Into produces a regular INSERT. See Insert Operations for the common API.

Notes

• Ignore and Update require an entity primary-key mapping; dbVisitor does not select another business unique key.
• Ignore skips matched rows only; validation, permission, and connection errors still fail.
• The result is a database update count, not an inserted-row or generated-key count.