Querying Microsoft SQL Server 2025 — Lesson 3: Functions, Aggregation, Transactions, and Troubleshooting

Topics Covered

• Apply aggregate functions, grouping, HAVING, and window functions
• Work with string, date, conversion, conditional, and analytical functions
• Handle errors and transactions while preserving data consistency
• Security, reliability, performance, support, and operational controls
• Common failure patterns, diagnostic evidence, and root-cause analysis
• Corrective actions, rollback considerations, and reusable runbook updates

Guided Practice Steps

1. Translate the lesson requirement into a clear Querying Microsoft SQL Server 2025 implementation or analysis objective.
2. Document assumptions, selected tools or features, dependencies, risks, and expected results.
3. Perform the guided task, capture evidence, and compare the result with the acceptance criteria.
4. Record issues, corrective actions, and a reusable operational or development note.

Practical Activity

Diagnose an incorrect aggregate result and redesign the query with transaction and error-handling safeguards.

• Define the scenario, inputs, constraints, and expected outcome.
• Complete the activity and preserve screenshots, outputs, logs, code, or decision evidence.
• Review the result, identify gaps, and document corrective or improvement actions.

Validation Checklist

• The stated requirement and expected outcome are clear.
• Configuration, code, data, or design decisions are documented.
• Normal, boundary, failure, security, and operational considerations are reviewed.
• Evidence supports the conclusion and the next action is prioritized.

Lesson Outcome

Learners can explain and apply Functions, Aggregation, Transactions, and Troubleshooting within a realistic Querying Microsoft SQL Server 2025 scenario and support the result with validation evidence.