SQL Database Migration Prompt

Write a database migration prompt for:

Current schema: {CURRENT_SCHEMA}
Desired change: {CHANGE} (e.g., Add column, split table)
Database type: {DB_TYPE}
Data volume: {VOLUME}

Generate:
1. UP script (to apply change)
2. DOWN script (to revert change)
3. Data backfill strategy (if needed)
4. Locking considerations (to avoid downtime)
5. Verification query