COMMIT TRANSACTION (Transact-SQL)
Marks the end of a successful implicit or explicit transaction. If @@TRANCOUNT is 1, COMMIT TRANSACTION makes all data modifications performed since the start of the transaction a permanent part of the database, frees the resources held by the transaction, and decrements @@TRANCOUNT to 0. If @@TRANCOUNT is greater than 1, COMMIT TRANSACTION decrements @@TRANCOUNT only by 1 and the transaction stays active.
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Syntax
COMMIT { TRAN | TRANSACTION } [ transaction_name | @tran_name_variable ] ]
[ ; ]
Arguments
transaction_name
Is ignored by the SQL Server Database Engine. transaction_name specifies a transaction name assigned by a previous BEGIN TRANSACTION. transaction_name must conform to the rules for identifiers, but cannot exceed 32 characters. transaction_name can be used as a readability aid by indicating to programmers which nested BEGIN TRANSACTION the COMMIT TRANSACTION is associated with.@tran_name_variable
Is the name of a user-defined variable containing a valid transaction name. The variable must be declared with a char, varchar, nchar, or nvarchar data type. If more than 32 characters are passed to the variable, only 32 characters will be used; the remaining characters are truncated.
Remarks
It is the responsibility of the Transact-SQL programmer to issue COMMIT TRANSACTION only at a point when all data referenced by the transaction is logically correct.
If the transaction committed was a Transact-SQL distributed transaction, COMMIT TRANSACTION triggers MS DTC to use a two-phase commit protocol to commit all of the servers involved in the transaction. If a local transaction spans two or more databases on the same instance of the Database Engine, the instance uses an internal two-phase commit to commit all of the databases involved in the transaction.
When used in nested transactions, commits of the inner transactions do not free resources or make their modifications permanent. The data modifications are made permanent and resources freed only when the outer transaction is committed. Each COMMIT TRANSACTION issued when @@TRANCOUNT is greater than 1 simply decrements @@TRANCOUNT by 1. When @@TRANCOUNT is finally decremented to 0, the entire outer transaction is committed. Because transaction_name is ignored by the Database Engine, issuing a COMMIT TRANSACTION referencing the name of an outer transaction when there are outstanding inner transactions only decrements @@TRANCOUNT by 1.
Issuing a COMMIT TRANSACTION when @@TRANCOUNT is 0 results in an error; there is no corresponding BEGIN TRANSACTION.
You cannot roll back a transaction after a COMMIT TRANSACTION statement is issued because the data modifications have been made a permanent part of the database.
The Database Engine in SQL Server 2000 and later increments the transaction count within a statement only when the transaction count is 0 at the start of the statement. In SQL Server version 7.0, the transaction count is always incremented regardless of the transaction count at the start of the statement. This can cause the value returned by @@TRANCOUNT in triggers to be lower in SQL Server 2000 and later than it is in SQL Server version 7.0.
In SQL Server 2000 and later, if a COMMIT TRANSACTION or COMMIT WORK statement is executed in a trigger and there is no corresponding explicit or implicit BEGIN TRANSACTION statement at the start of the trigger, users may see different behavior than in SQL Server version 7.0. Placing COMMIT TRANSACTION or COMMIT WORK statements in a trigger is not recommended.
Permissions
Requires membership in the public role.
Examples
A. Committing a transaction
The following example deletes a job candidate.
USE AdventureWorks2008R2;
GO
BEGIN TRANSACTION;
GO
DELETE FROM HumanResources.JobCandidate
WHERE JobCandidateID = 13;
GO
COMMIT TRANSACTION;
GO
B. Committing a nested transaction
The following example creates a table, generates three levels of nested transactions, and then commits the nested transaction. Although each COMMIT TRANSACTION statement has a transaction_name parameter, there is no relationship between the COMMIT TRANSACTION and BEGIN TRANSACTION statements. The transaction_name parameters are simply readability aids to help the programmer ensure that the proper number of commits are coded to decrement @@TRANCOUNT to 0 and thereby commit the outer transaction.
USE AdventureWorks2008R2;
GO
IF OBJECT_ID(N'TestTran',N'U') IS NOT NULL
DROP TABLE TestTran;
GO
CREATE TABLE TestTran (Cola int PRIMARY KEY, Colb char(3));
GO
-- This statement sets @@TRANCOUNT to 1.
BEGIN TRANSACTION OuterTran;
GO
PRINT N'Transaction count after BEGIN OuterTran = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO
INSERT INTO TestTran VALUES (1, 'aaa');
GO
-- This statement sets @@TRANCOUNT to 2.
BEGIN TRANSACTION Inner1;
GO
PRINT N'Transaction count after BEGIN Inner1 = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO
INSERT INTO TestTran VALUES (2, 'bbb');
GO
-- This statement sets @@TRANCOUNT to 3.
BEGIN TRANSACTION Inner2;
GO
PRINT N'Transaction count after BEGIN Inner2 = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO
INSERT INTO TestTran VALUES (3, 'ccc');
GO
-- This statement decrements @@TRANCOUNT to 2.
-- Nothing is committed.
COMMIT TRANSACTION Inner2;
GO
PRINT N'Transaction count after COMMIT Inner2 = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO
-- This statement decrements @@TRANCOUNT to 1.
-- Nothing is committed.
COMMIT TRANSACTION Inner1;
GO
PRINT N'Transaction count after COMMIT Inner1 = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO
-- This statement decrements @@TRANCOUNT to 0 and
-- commits outer transaction OuterTran.
COMMIT TRANSACTION OuterTran;
GO
PRINT N'Transaction count after COMMIT OuterTran = '
+ CAST(@@TRANCOUNT AS nvarchar(10));
GO