SQL Server Interview Topic 29: Error Handling and Safe Transactions

This topic checks whether you can protect data when something goes wrong.

🎯 Interview Goal

You should be able to explain how SQL Server changes can be rolled back safely when an error happens.

Q180. Why is error handling important in SQL?

Quick interview answer:

Error handling helps stop partial or wrong data changes. If one step fails during an important operation, the database should not be left in a half-updated state.

Study in detail: Transactions and Concurrency - This article explains safe data changes.

Q181. What is TRY CATCH in SQL Server?

Quick interview answer:

TRY CATCH lets SQL Server run code in a try block and handle errors in a catch block. It is commonly used with transactions so failed work can be rolled back.

Study in detail: Stored Procedures and Functions - This lesson explains stored procedure patterns.

Q182. When should you use ROLLBACK?

Quick interview answer:

Use ROLLBACK when a transaction should be undone because an error happened or validation failed. For example, if fee payment is updated but fee history insert fails, rollback both.

Study in detail: Transactions and Concurrency - This lesson explains rollback.

Q183. What should be logged when a database error happens?

Quick interview answer:

Log what operation failed, when it failed, useful ids, and the error message. Avoid logging sensitive data like passwords or private information.

Study in detail: Troubleshooting and Security - These lessons explain safe troubleshooting.

Q184. How do you validate before changing data?

Quick interview answer:

Check whether the target row exists, whether input values are valid, and whether the business rule allows the change. Validation reduces errors before the transaction starts.

Study in detail: Constraints - This article explains database rules.

💡 Interview Tip

In error handling answers, always mention data consistency and rollback.