单项选择题 Which of the following best describes how locks are used in DB2?（）

单项选择题 Which of the following resources can be explicitly locked?（）

单项选择题 Given table T1 has column I1 containing the following data: I1 1 2 3 4 If the following sequence of SQL statements is applied within a single unit of work: UPDATE t1 SET i1 = 3 WHERE i1 = 2; S AVEPOINT s1 ON ROLLBACK RETAIN CURSORS; UPDATE t1 SET i1 = 5 WHERE i1 = 3; SAVEPOINT s2 ON ROLLBACK RETAIN CURSORS;INSERT INTO t1 (i1) VALUES (6); ROLLBACK TO SAVEPOINT s1; UPDATE t1 SET i1 = 2 WHERE i1 = 4; COMMIT; What is the expected sequence of values returned from?（） SELECT i1 FROM t1 ORDER BY i1