data-migration-scripts

data-migration-scripts is a skill for Claude Code, Codex from aj-geddes/useful-ai-prompts. It costs 45 tokens per session (781 once invoked), scanned A, original, MIT.

A guide to writing database migration scripts, which safely change table structures or transform existing data. It includes checks, rollback steps, and ways to make changes with little or no downtime.

In plain words
What is it for?
Use it to add or change columns, move data between systems, clean up or reshape records, split or merge tables, and backfill new fields.
Why use it?
It reduces the risk of losing or corrupting data when changing a live database. Reversible steps and validation make schema changes and large data updates easier to recover from.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to add or change columns, move data between systems, clean up or reshape records, split or merge tables, and backfill new fields.

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Install with agentmods
npx agentmods add skills/aj-geddes/useful-ai-prompts/data-migration-scripts
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add aj-geddes/useful-ai-prompts --skill data-migration-scripts
Clone the repo
git clone --depth 1 https://github.com/aj-geddes/useful-ai-prompts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for data-migration-scripts

README.md
[![agentmods](https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/data-migration-scripts/github.svg)](https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/data-migration-scripts)
Your own site
<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/data-migration-scripts"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/data-migration-scripts/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for data-migration-scripts

Your own site · 80×15
<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/data-migration-scripts"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/data-migration-scripts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 781 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 18 Mar 2026
  • Snyk pass 4 Mar 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00045 $0.00781
Opus 5 $0.00023 $0.00391
Sonnet 5 $0.00009 $0.00156
Haiku 4.5 $0.00005 $0.00078

Measured 9d ago against content hash 6ee2bf4efb24, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

data-migration-scripts scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-schema.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/data-migration-scripts/SKILL.md · 110 lines

How it starts

The opening of the file, as written. The whole thing — 110 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Data Migration Scripts

Table of Contents

Overview

Create robust, safe, and reversible data migration scripts for database schema changes and data transformations with minimal downtime.

When to Use

  • Database schema changes
  • Adding/removing/modifying columns
  • Migrating between database systems
  • Data transformations and cleanup
  • Splitting or merging tables
  • Changing data types
  • Adding indexes and constraints
  • Backfilling data
  • Multi-tenant data migrations

Quick Start

Minimal working example:

import { Knex } from "knex";

// migrations/20240101000000_add_user_preferences.ts
export async function up(knex: Knex): Promise<void> {
  // Create new table
  await knex.schema.createTable("user_preferences", (table) => {
    table.uuid("id").primary().defaultTo(knex.raw("gen_random_uuid()"));
    table
      .uuid("user_id")
      .notNullable()
      .references("id")
      .inTable("users")
      .onDelete("CASCADE");
    table.jsonb("preferences").defaultTo("{}");
    table.timestamp("created_at").defaultTo(knex.fn.now());
    table.timestamp("updated_at").defaultTo(knex.fn.now());

    table.index("user_id");
  });

  // Migrate existing data
  await knex.raw(`
    INSERT INTO user_preferences (user_id, preferences)
    SELECT id, jsonb_build_object(
      'theme', COALESCE(theme, 'light'),
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide Contents
Knex.js Migrations (Node.js) Knex.js Migrations (Node.js)
Alembic Migrations (Python/SQLAlchemy) Alembic Migrations (Python/SQLAlchemy)
Large Data Migration with Batching Large Data Migration with Batching
Zero-Downtime Migration Pattern Zero-Downtime Migration Pattern
Migration Validation Migration Validation
Cross-Database Migration Cross-Database Migration

Read the full file on GitHub · 110 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 110 lines · 45 tokens per session scan A 6ee2bf4efb24

Subscribe to this mod's changes

data-migration-scripts is a skill published in the GitHub repository aj-geddes/useful-ai-prompts (338 stars, last pushed 6mo ago), licensed MIT. It adds 45 tokens to every session and 781 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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