THIS TOPIC APPLIES TO: SQL Server Azure SQL Database Azure SQL Data Warehouse Parallel Data Warehouse
Returns the lock mode held by the lock owner on a particular application resource. APPLOCK_MODE is an application lock function, and it operates on the current database. The scope of application locks is the database.
Is the user, role, or application role that can be granted permissions to objects in the database. The caller of the function must be a member of database_principal, dbo, or the db_owner fixed database role in order to call the function successfully.
Is a lock resource name specified by the client application. The application must ensure that the resource name is unique. The specified name is hashed internally into a value that can be stored in the SQL Server lock manager. resource_name is nvarchar(255) with no default. resource_name is binary compared, and is case-sensitive regardless of the collation settings of the current database.
Is the owner of the lock, which is the lock_owner value when the lock was requested. lock_owner is nvarchar(32), and the value can be either Transaction (the default) or Session.
Returns the lock mode held by the lock owner on a particular application resource. Lock mode can be any one of these values:
*This lock mode is a combination of other lock modes and cannot be explicitly acquired by using sp_getapplock.
Two users (User A and User B) with separate sessions run the following sequence of Transact-SQL statements.
User A runs:
USE AdventureWorks2012; GO BEGIN TRAN; DECLARE @result int; EXEC @result=sp_getapplock @DbPrincipal='public', @Resource='Form1', @LockMode='Shared', @LockOwner='Transaction'; SELECT APPLOCK_MODE('public', 'Form1', 'Transaction'); GO
User B then runs:
Use AdventureWorks2012; GO BEGIN TRAN; SELECT APPLOCK_MODE('public', 'Form1', 'Transaction'); --Result set: NoLock SELECT APPLOCK_TEST('public', 'Form1', 'Shared', 'Transaction'); --Result set: 1 (Lock is grantable.) SELECT APPLOCK_TEST('public', 'Form1', 'Exclusive', 'Transaction'); --Result set: 0 (Lock is not grantable.) GO
User A then runs:
EXEC sp_releaseapplock @Resource='Form1', @DbPrincipal='public'; GO
User B then runs:
SELECT APPLOCK_TEST('public', 'Form1', 'Exclusive', 'Transaction'); --Result set: '1' (The lock is grantable.) GO
User A and User B then run:
COMMIT TRAN; GO