SQL Server THROW Statement - Error Handling Tutorial

What is the THROW Statement?

THROW is a Transact-SQL statement used to raise an exception and transfer control to the CATCH block or return an error to the client.

It can be used to raise a new error or re-throw an existing error caught in a TRY CATCH block.

• Introduced in SQL Server 2012.
• Replaces many use cases of RAISERROR.
• Simplifies error propagation.

THROW Syntax and Usage

The THROW statement has two main forms: with parameters to raise a new error, or without parameters to re-throw the current error inside a CATCH block.

• THROW [error_number, message, state];
• THROW; -- re-throws the current error

Using THROW in TRY CATCH Blocks

THROW is commonly used inside the CATCH block of a TRY CATCH construct to handle errors gracefully.

You can either raise a new error or re-throw the caught error to propagate it.

• Use THROW; to re-throw the caught error without losing error details.
• Use THROW with parameters to raise a custom error.

Comparison: THROW vs RAISERROR

While RAISERROR has been used historically for error handling, THROW offers advantages in simplicity and functionality.

THROW automatically preserves the original error number and message when re-throwing errors.

• THROW requires SQL Server 2012 or later; RAISERROR works in older versions.
• RAISERROR supports custom severity levels; THROW does not allow severity below 11.
• THROW syntax is simpler and less error-prone.