---
description: Database and Flyway migration rules for HealthLink-HIS
paths:
  - "**/*.sql"
  - "**/mapper/*.xml"
  - "healthlink-his-server/**/resources/db/migration/**"
---

# Database and Migration Rules

## Iron Law 2: Flyway database migration
- All new tables or new fields require a Flyway migration script
- Path: `healthlink-his-application/src/main/resources/db/migration/`
- Naming: `V{version}__{description}.sql` (double underscore)

## Iron Law 17: Database iron laws
- **Query real database before modification** — confirm table structure, field constraints, indexes
- **No guessing SQL** — check table structure first
- **Verify after SQL modification** — use `EXPLAIN` or actual query to verify syntax
- **Check NOT NULL constraints** — verify `is_nullable` before INSERT/UPDATE
- **Check all related tables** — for JOIN queries, check all related table structures and foreign keys

## Iron Law 18: SQL migration restrictions
- Only `ALTER TABLE ADD COLUMN` allowed
- No `DROP COLUMN` or `RENAME COLUMN`
- New fields can only be appended, not deleted or renamed

## Database connection
- PostgreSQL 15+ at `192.168.110.252:15432`
- Database: `healthlink_his`
- Flyway is enabled in dev and runs on startup
- Migration conflicts will block server startup

## Full chain 6-ring analysis
For bugs/requirements involving database fields, follow the complete chain:
```
Frontend/Page → Controller → Service → Mapper → DB/SQL → Related modules
 ①Input         ②Validate   ③Business  ④Persist   ⑤Storage  ⑥Linkage
```

| Ring | Check |
|------|-------|
| ① Input | Frontend has input entry (dialog, table row edit, form) |
| ② Validate | Controller parameter validation, @Valid, permission control |
| ③ Business | Service business logic, transaction boundaries, multiple Service implementation entries |
| ④ Persist | Mapper XML, DTO field mapping, type conversion |
| ⑤ Storage | Database table structure, indexes, NOT NULL constraints |
| ⑥ Linkage | Upstream (orders→nurse station), downstream (printing, billing, reports) synchronization |