Example: Updating IDENTITY defined as GENERATED BY DEFAULT

CREATE TABLE Test_sqlUpdateByDefault (
    idValue INTEGER GENERATED BY DEFAULT AS IDENTITY,
    acctNum LONG,
    name STRING,
primary key(acctNum));

INSERT INTO Test_sqlUpdateByDefault VALUES (DEFAULT, 123456, 'joe');
INSERT INTO Test_sqlUpdateByDefault VALUES (400, 23456,'sam');
INSERT INTO Test_sqlUpdateByDefault VALUES (500, 34567,'carl');

Table Test-sqlUpdateByDefault will have the following rows:

1, 123456, 'joe'
400, 23456, 'jasmine'
500, 34567, 'carl'

UPDATE Test_sqlUpdateByDefault 
SET idValue = 100 
WHERE acctNum = 123456;

The above UPDATE statement will replace row (1, 123456, 'joe') with (100, 123456, 'joe') in the database.