• Exclusive lock(Write lock): The locked data can only be displayed or edited by a single user. A request for another exclusive lock or for a shared lock is rejected.
• Shared lock(Read lock): More than one user can access the locked data at the same time in display mode. A request for another shared lock is accepted, even if it comes from another user. An exclusive lock is rejected.
• Exclusive but not cumulative(Enhanced write lock): Exclusive locks can be requested several times from the same transaction and are processed successively. In contrast, exclusive but not cumulative locks can be called only once from the same transaction. All other lock requests are rejected.
• Shared lock(Read lock): More than one user can access the locked data at the same time in display mode. A request for another shared lock is accepted, even if it comes from another user. An exclusive lock is rejected.
• Exclusive but not cumulative(Enhanced write lock): Exclusive locks can be requested several times from the same transaction and are processed successively. In contrast, exclusive but not cumulative locks can be called only once from the same transaction. All other lock requests are rejected.