9-04 nested transactions and transaction classifications (1)

Global variable @ @TRANCOUNT:

Returns the number of active transactions for the current connection.

An explicit transaction:

Begin TRANSACTION The beginning of a clear real transaction.

The most common type of transaction.

Implicit transactions:

By setting the Setimplicit_transactions on statement,

Sets the stealth transaction mode to open.

The subsequent T-SQL statement automatically starts a new transaction.

Commits or rolls back a transaction, and the next T-SQL statement starts a new transaction.

Commit transactions automatically:

The default mode for SQL Sever.

Each individual T-SQL statement is a transaction.

--commit effect on transaction number (nested transactions used) print  @ @TRANCOUNT--look at the number of transactions without a transaction begin  tran--start transaction     PRINT @@ trancount--start Transaction, @ @TRANCOUNT will be set to 1      begin  tran--start transaction      PRINT  @ @TRANCOUNT--Number of transactions plus 1      COMMIT  tran--Commit Second transaction      print @ @TRANCOUNT--Number of transactions minus 1      commit TRAN--commit first transaction, number of transactions minus 1      PRINT @ @TRANCOUNT     GO

Operation Result:

9-04 nested transactions and transaction classifications (1)