How Does SQL Server Handle Errors Within Transactions, and How Can I Ensure Rollback?

SQL Server Transactions and Error Handling

When using transactions in SQL Server, it is critical to understand the behavior when errors are encountered.

In the example, a SQL Server transaction containing multiple INSERT statements is executed as a single long string command. If any INSERT statement fails, it must be determined whether the entire transaction is automatically rolled back.

SQL Server Transaction Behavior

By default, SQL Server does not automatically roll back transactions when an error is encountered. If a command within a transaction fails, the entire transaction remains open and committed, even if subsequent commands also fail. This means that changes made by a successful command will be permanent.

Force transaction rollback

To ensure that transactions are rolled back when an error occurs, there are two methods:

1. SET XACT_ABORT ON: This command can be executed before starting a transaction. When set, SQL Server automatically rolls back the transaction if any statement in the transaction fails.
2. Explicit ROLLBACK: If XACT_ABORT is not set, the transaction can be manually rolled back using an explicit ROLLBACK statement.

Suggestion

It is recommended to use SET XACT_ABORT ON before starting a transaction. This ensures consistent behavior and avoids the need for explicit rollback statements. In this case, if one INSERT statement in the example transaction fails, SQL Server automatically rolls back the entire transaction, undoing any changes made by the successful statement.

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