Insomnia can be caused by psychiatric conditions such as depression. Psychological struggles can make it hard to sleep, insomnia itself can bring on changes in mood, and shifts in hormones and physiology can lead to both psychiatric issues and insomnia at the same time.
Lock modes specify different kinds of locks. The choice of which lock mode to apply depends on the resource that needs to be locked. The following three lock types are used for row-and page-level locking: 1  Shared (S). 2  Exclusive (X).3  Update (U).nce an exclusive lock is set for the page (or row), no other lock can be placed on the same resource. NOTE. The database system automatically chooses the appropriate lock mode according to the operation type (read or write). An update lock can be placed only if no other update or exclusive lock exists.
The Microsoft SQL Server Database Engine locks resources using different lock modes that determine how the resources can be accessed by concurrent transactions. Applies to: SQL Server 2008 R2 and higher versions. The following table shows the resource lock modes that the Database Engine uses. Lock mode. Description. Shared (S). Used for read operations that do not change or update data, such as a SELECT statement. Update (U). Used on resources that can be updated.