SQL Server - What are some Best Practices For Exception (Error) Handling?

Proper error handling in SQL Server ensures smooth database operations and prevents unexpected failures. Here are some best practices for handling errors effectively.

Use TRY...CATCH Blocks

1) Encapsulate risky SQL statements within a TRY block.

2) Capture and handle errors in the CATCH block.

3) This prevents the entire transaction from failing due to unexpected errors.

Log Errors for Debugging

It is always advisable to log errors, if at all they ever occur during a process.

• Store error details in a log table for future analysis.

• Use ERROR_MESSAGE(), ERROR_NUMBER() and ERROR_SEVERITY() functions to retrieve error details. These are system functions.

1) ERROR_MESSAGE(): Returns the message text of the error. See this example.

2) ERROR_NUMBER(): Provides the error number.

3) ERROR_SEVERITY(): Indicates the severity level of the error.

Example:

Here's an example using ERROR_MESSAGE(), ERROR_NUMBER() and ERROR_SEVERITY() functions.

BEGIN TRY
    SELECT 1 / 0;   -- Trying to divide by zero, which will cause an error.
END TRY
BEGIN CATCH
    -- Retrieve and display error details.
    SELECT 
        ERROR_NUMBER() AS ErrorNumber,
        ERROR_MESSAGE() AS ErrorMessage,
        ERROR_SEVERITY() AS ErrorSeverity;
END CATCH;

Output

exception handling using sql server system functions

Implement Proper Transaction Handling

• Use BEGIN TRANSACTION, COMMIT, and ROLLBACK to maintain data integrity.

• Roll back changes if an error occurs to avoid incomplete or corrupted data.

Handle Specific Error Types

• Use ERROR_NUMBER() to identify error codes.

• Define custom messages for recurring errors using RAISEERROR.

Avoid Hardcoded Error Handling

• Rely on dynamic error handling rather than hardcoded conditions.

• This makes error management more scalable.

Monitor and Alert

• Set up automated alerts to notify administrators of serious errors.

• Use SQL Server Agent to track error logs periodically.

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