# Django迁移不可逆错误：迁移0002_auto无法回滚

- **ID:** `python/django-migration-irreversible`
- **领域:** python
- **类别:** data_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

迁移包含不可逆的操作，例如没有反向代码的RunSQL。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.x | active | — | — |

## 解决方案

1. **Add reverse code to RunSQL operations** (90% 成功率)
   ```
   migrations.RunSQL(sql, reverse_sql='DROP TABLE ...')
   ```
2. **Create a new migration to revert changes** (85% 成功率)
   ```
   Generate a new migration that reverses the effects.
   ```

## 无效尝试

- **Forcing reverse migration with --fake** — May leave database in inconsistent state. (80% 失败率)
- **Deleting migration files** — Breaks migration chain; may cause future errors. (70% 失败率)