# SQL Migrations > SQL and database migration best practices for safe schema changes Use when this capability is needed. - Skill: `tomevault-io/sql-migrations` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/sql-migrations` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/sql-migrations/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Data & Analytics - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/sql-migrations --- ## What I do - Enforce safe migration patterns with rollback support - Apply schema design rules for constraints, indexes, and data integrity - Guide destructive change management and data backfill strategies ## When to use me Use this when writing database migrations, schema changes, or data transformation scripts. ## Key Rules - Migrations must be idempotent where possible; always provide down/rollback steps - Never drop data or tables without explicit approval and confirmed backups - Use explicit versions or timestamps; keep migration order deterministic - Stage destructive changes (drops, renames) separately from data moves — never in the same migration - Test migrations against a prod-like snapshot before deploying to production - Declare explicit column types and constraints: PK, FK, UNIQUE, CHECK, NOT NULL on every column - Add indexes for join columns and common filter predicates; avoid over-indexing - Wrap DDL statements in transactions when the database supports it; guard against lock escalation on large tables - Always include `WHERE` clauses on UPDATE and DELETE — never allow unintended full-table changes - Use UTC timezone and consistent collation/charset across the entire schema - Backfill data in batches — never use single massive statements that lock tables - Avoid `SELECT *` in views and procedures; specify columns explicitly - Avoid long-running blocking migrations during peak traffic; prefer phased rollouts - Use a verify-fix-verify loop: run the validation commands below, fix any failures, and rerun until all checks pass ## Validation Commands ```bash sqlfluff lint || true ``` --- > Source: [shahboura/agents-opencode](https://github.com/shahboura/agents-opencode) — distributed by [TomeVault](https://tomevault.io).