Instruction file imported from raffertyuy/github-copilot-prompts (.github/instructions/sql.instructions.md). Copyright stays with the author.

T-SQL Coding Best Practices

SQL-Specific Guidelines

• Use uppercase for T-SQL keywords and lowercase for identifiers.
• Avoid using reserved words as object names.
• Always terminate statements with a semicolon.
• Use schema names when referencing objects (e.g., dbo.TableName).
• Avoid using SELECT *; explicitly specify required columns.

Formatting

• Place each statement on its own line.
• Align related clauses (e.g., SELECT, FROM, WHERE, JOIN) vertically.
• Use consistent casing for identifiers and keywords.

Error Handling

• Use TRY...CATCH blocks for error handling in stored procedures and scripts.
• Log error messages and error numbers for troubleshooting.

Performance

• Use appropriate indexes to optimize query performance.
• Avoid using cursors when set-based operations are possible.
• Use EXISTS instead of COUNT(*) for existence checks.
• Avoid scalar functions in SELECT statements; prefer inline table-valued functions.
• Use table variables or temporary tables judiciously.

Security

• Grant the least privilege necessary to users and roles.
• Avoid using the sa account for application connections.

Maintainability

• Use consistent naming conventions (e.g., PascalCase or snake_case).
• Document stored procedures, functions, and complex queries with comments.
• Break down large scripts into smaller, reusable modules.

Version Control

• Store all database scripts in version control.
• Use clear and descriptive commit messages for database changes.