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BEGIN TRANSACTION (Transact-SQL)

  • Artikkeli

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) Warehouse in Microsoft Fabric

Marks the starting point of an explicit, local transaction. Explicit transactions start with the BEGIN TRANSACTION statement and end with the COMMIT or ROLLBACK statement.

Transact-SQL syntax conventions

Syntax

Syntax for SQL Server, Azure SQL Database, and Azure SQL Managed Instance.

BEGIN { TRAN | TRANSACTION }
    [ { transaction_name | @tran_name_variable }
      [ WITH MARK [ 'description' ] ]
    ]
[ ; ]

Syntax for Synapse Data Warehouse in Microsoft Fabric, Azure Synapse Analytics and Analytics Platform System (PDW).

BEGIN { TRAN | TRANSACTION }
[ ; ]

Arguments

transaction_name

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, and Azure SQL Managed Instance

The name assigned to the transaction. transaction_name must conform to the rules for identifiers, but identifiers longer than 32 characters aren't allowed. Use transaction names only on the outermost pair of nested BEGIN...COMMIT or BEGIN...ROLLBACK statements. transaction_name is always case sensitive, even when the instance of SQL Server isn't case sensitive.

@tran_name_variable

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, and Azure SQL Managed Instance

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 the first 32 characters are used. The remaining characters are truncated.

WITH MARK [ 'description' ]

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, and Azure SQL Managed Instance

Specifies that the transaction is marked in the log. description is a string that describes the mark. A description longer than 128 characters is truncated to 128 characters before being stored in the msdb.dbo.logmarkhistory table.

If WITH MARK is used, a transaction name must be specified. WITH MARK allows for restoring a transaction log to a named mark.

Remarks

BEGIN TRANSACTION increments @@TRANCOUNT by 1.

BEGIN TRANSACTION represents a point at which the data referenced by a connection is logically and physically consistent. If errors are encountered, all data modifications made after the BEGIN TRANSACTION can be rolled back to return the data to this known state of consistency. Each transaction lasts until either it completes without errors and COMMIT TRANSACTION is issued to make the modifications a permanent part of the database, or errors are encountered and all modifications are erased with a ROLLBACK TRANSACTION statement.

BEGIN TRANSACTION starts a local transaction for the connection issuing the statement. Depending on the current transaction isolation level settings, many resources acquired to support the Transact-SQL statements issued by the connection are locked by the transaction until it completes with either a COMMIT TRANSACTION or ROLLBACK TRANSACTION statement. Transactions left outstanding for long periods of time can prevent other users from accessing these locked resources, and also can prevent log truncation.

Although BEGIN TRANSACTION starts a local transaction, it isn't recorded in the transaction log until the application then performs an action that must be recorded in the log, such as executing an INSERT, UPDATE, or DELETE statement. An application can perform actions such as acquiring locks to protect the transaction isolation level of SELECT statements, but nothing is recorded in the log until the application performs a modification action.

Naming multiple transactions in a series of nested transactions with a transaction name has little effect on the transaction. Only the first (outermost) transaction name is registered with the system. A rollback to any other name (other than a valid savepoint name) generates an error. None of the statements executed before the rollback is, in fact, rolled back at the time this error occurs. The statements are rolled back only when the outer transaction is rolled back.

The local transaction started by the BEGIN TRANSACTION statement is escalated to a distributed transaction if the following actions are performed before the statement is committed or rolled back:

  • An INSERT, DELETE, or UPDATE statement that references a remote table on a linked server is executed. The INSERT, UPDATE, or DELETE statement fails if the OLE DB provider used to access the linked server doesn't support the ITransactionJoin interface.

  • A call is made to a remote stored procedure when the REMOTE_PROC_TRANSACTIONS option is set to ON.

The local copy of SQL Server becomes the transaction controller and uses Microsoft Distributed Transaction Coordinator (MS DTC) to manage the distributed transaction.

A transaction can be explicitly executed as a distributed transaction by using BEGIN DISTRIBUTED TRANSACTION. For more information, see BEGIN DISTRIBUTED TRANSACTION.

When SET IMPLICIT_TRANSACTIONS is set to ON, a BEGIN TRANSACTION statement creates two nested transactions. For more information, see SET IMPLICIT_TRANSACTIONS.

Marked transactions

The WITH MARK option causes the transaction name to be placed in the transaction log. When you restore a database to an earlier state, the marked transaction can be used in place of a date and time. For more information, see Use Marked Transactions to Recover Related Databases Consistently and RESTORE Statements.

Additionally, transaction log marks are necessary if you need to recover a set of related databases to a logically consistent state. Marks can be placed in the transaction logs of the related databases by a distributed transaction. Recovering the set of related databases to these marks results in a set of databases that are transactionally consistent. Placement of marks in related databases requires special procedures.

The mark is placed in the transaction log only if the database is updated by the marked transaction. Transactions that don't modify data aren't marked.

BEGIN TRANSACTION <new_name> WITH MARK can be nested within an already existing transaction that isn't marked. Upon doing so, <new_name> becomes the mark name for the transaction, despite the name that the transaction might already have been given. In the following example, M2 is the name of the mark.

BEGIN TRAN T1;

UPDATE table1 ...;

BEGIN TRAN M2 WITH MARK;
UPDATE table2 ...;
SELECT * from table1;

COMMIT TRAN M2;

UPDATE table3 ...;

COMMIT TRAN T1;

When you nest transactions, you receive the following warning message if you try to mark a transaction that is already marked:

Server: Msg 3920, Level 16, State 1, Line 3
WITH MARK option only applies to the first BEGIN TRAN WITH MARK.
The option is ignored.

Permissions

Requires membership in the public role.

Examples

The Transact-SQL code samples in this article use the AdventureWorks2022 or AdventureWorksDW2022 sample database, which you can download from the Microsoft SQL Server Samples and Community Projects home page.

A. Use an explicit transaction

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, Azure SQL Managed Instance, Azure Synapse Analytics, Analytics Platform System (PDW)

BEGIN TRANSACTION;
DELETE FROM HumanResources.JobCandidate
    WHERE JobCandidateID = 13;
COMMIT;

B. Rolling back a transaction

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, Azure SQL Managed Instance, Azure Synapse Analytics, Analytics Platform System (PDW)

The following example shows the effect of rolling back a transaction. In this example, the ROLLBACK statement rolls back the INSERT statement, but the created table still exists.

CREATE TABLE ValueTable (id INT);
BEGIN TRANSACTION;
    INSERT INTO ValueTable VALUES(1);
    INSERT INTO ValueTable VALUES(2);
ROLLBACK;

C. Name a transaction

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, Azure SQL Managed Instance

The following example shows how to name a transaction.

DECLARE @TranName VARCHAR(20);
SELECT @TranName = 'MyTransaction';

BEGIN TRANSACTION @TranName;
USE AdventureWorks2022;
DELETE FROM AdventureWorks2022.HumanResources.JobCandidate
    WHERE JobCandidateID = 13;

COMMIT TRANSACTION @TranName;
GO

D. Mark a transaction

Applies to: SQL Server 2008 (10.0.x) and later versions, Azure SQL Database, Azure SQL Managed Instance

The following example shows how to mark a transaction. The transaction CandidateDelete is marked.

BEGIN TRANSACTION CandidateDelete
    WITH MARK N'Deleting a Job Candidate';
GO
USE AdventureWorks2022;
GO
DELETE FROM AdventureWorks2022.HumanResources.JobCandidate
    WHERE JobCandidateID = 13;
GO
COMMIT TRANSACTION CandidateDelete;
GO

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