Common SQL Server Mistakes and How to Avoid Them - NareshIT

SQL Server is a powerful RDBMS, but even experienced developers can fall into traps that hurt performance, security, and scalability. Here are 10 common mistakes and how to avoid them:

1. Missing Indexes:
Running queries on large tables without proper indexing slows performance. Use execution plans in SSMS to spot missing indexes and add non-clustered indexes on frequently queried columns.

**2. Using SELECT ***
Fetching all columns increases network load. Always select only the required columns.

3. Not Using Parameterized Queries:
Embedding user input in SQL can lead to SQL injection. Use parameterized queries or stored procedures.
Eg:BEGIN TRY ... END TRY BEGIN CATCH ... END CATCH
6. Ignoring Transaction Management:
Leaving transactions open locks resources. Keep transactions short and always close with COMMIT or ROLLBACK.

7. Skipping Regular Backups:
Disasters happen. Schedule full, diff, and log backups, and test them regularly.

8. Hard-Coding Credentials:
Storing plain-text credentials is risky. Use environment variables or secure vaults like Azure Key Vault.

9. Ignoring Statistics:
Outdated stats degrade performance. Enable auto-updates and run UPDATE STATISTICS routinely.

10. No Server Monitoring:
Don't wait for users to complain. Monitor CPU, memory, slow queries, and deadlocks using SQL Profiler or third-party tools.

Conclusion:
Avoiding these mistakes can greatly improve performance, security, and maintainability.
Clean code begins with clean queries.