Sqlserver Expert

SQL Server Expert

Act as DBA and developer expert in Microsoft SQL Server.

Quick Reference

CTEs with Window Functions

WITH RankedData AS (
  SELECT Id, Name, Department,
    ROW_NUMBER() OVER (PARTITION BY Department ORDER BY HireDate) AS RowNum,
    SUM(Salary) OVER (PARTITION BY Department) AS DeptTotal
  FROM Employees
)
SELECT * FROM RankedData WHERE RowNum = 1;

MERGE Statement

MERGE INTO Target AS t
USING Source AS s ON t.Id = s.Id
WHEN MATCHED THEN UPDATE SET t.Name = s.Name
WHEN NOT MATCHED THEN INSERT (Id, Name) VALUES (s.Id, s.Name)
WHEN NOT MATCHED BY SOURCE THEN DELETE;

Pagination

SELECT * FROM Orders ORDER BY OrderDate DESC
OFFSET @PageSize * (@PageNumber - 1) ROWS FETCH NEXT @PageSize ROWS ONLY;

Best Practices

Performance

1. Avoid SELECT * - list columns explicitly
2. Use appropriate indexes for WHERE/JOIN columns
3. Avoid functions on columns in WHERE (not sargable)
4. Use SET NOCOUNT ON in stored procedures
5. Use OPTION (RECOMPILE) for parameter-sensitive queries

Security

1. Never concatenate strings - use parameters
2. Least privilege for application users
3. Use schemas to organize and control access

Detailed References

• T-SQL Advanced Patterns: See [references/tsql-advanced.md](references/tsql-advanced.md)
• .NET Core Integration: See [references/dotnet-integration.md](references/dotnet-integration.md)
• Performance Tuning & Deadlocks: See [references/performance.md](references/performance.md)
• Change Data Capture (CDC): See [references/cdc.md](references/cdc.md)
• System Queries & Metadata: See [references/system-queries.md](references/system-queries.md)

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: cuongtl1992
• Source: cuongtl1992/vibe-skills
• License: MIT

Install and usage instructions live in the source repository linked above.