SQL Server Error Handling with RAISERROR

What is RAISERROR?

RAISERROR is a Transact-SQL statement used to raise an error message and initiate error handling in SQL Server.

It can send messages to the client, log errors, and influence transaction behavior depending on the severity level.

• Raises user-defined error messages.
• Supports message formatting with parameters.
• Controls error severity and state.
• Can be used to trigger TRY...CATCH blocks.

RAISERROR Syntax and Parameters

The basic syntax of RAISERROR includes specifying the message text or message ID, severity level, and state.

You can also include parameters to format the message dynamically.

• Message: Either a string literal or a message ID from sys.messages.
• Severity: Integer from 0 to 25 indicating the error severity.
• State: Integer from 0 to 255 used to indicate error location or state.
• Optional parameters for message formatting.

Severity Levels Explained

Severity levels in RAISERROR determine how SQL Server treats the error. They range from informational messages to fatal errors.

Understanding severity helps you decide how to handle errors in your code.

• 0-10: Informational messages, do not cause errors.
• 11-16: User-defined errors, typically used for routine errors.
• 17-19: Software or hardware errors, more serious.
• 20-25: Fatal errors, usually terminate the connection.

Using RAISERROR in Practice

RAISERROR is commonly used inside stored procedures or scripts to signal errors and control flow.

It works well with TRY...CATCH blocks to handle exceptions gracefully.

• Raise an error when a business rule is violated.
• Abort transactions on critical failures.
• Log custom error messages for debugging.
• Notify client applications of specific error conditions.

Example: RAISERROR Usage

Here is a simple example demonstrating RAISERROR raising a custom error with severity 16 and state 1.