sql-best-practices

name	sql-best-practices
description	Use this skill when writing SQL queries — selects, joins, aggregations, window functions, or schema modifications. Apply whenever SQL is needed to ensure correctness, safety, and performance.
category	data_analysis

SQL Best Practices

Query quality:

• Use SELECT col1, col2 — never SELECT * in production code.
• Use CTEs (WITH) for readability instead of deeply nested subqueries.
• Filter early: apply WHERE before JOIN when possible to reduce data scanned.
• Use EXPLAIN / EXPLAIN ANALYZE to inspect query plans for slow queries.

Safety:

• Always use parameterized queries from application code — never string interpolation.
• Wrap destructive operations (DELETE, UPDATE, DROP) in a transaction.
• Test on a staging/dev environment before running on production.

Naming: snake_case for tables/columns, descriptive names, consistent pluralization.