```mermaid
graph LR
1((1)) --> |需求分析 3天| 2((2))
1 --> |系统设计 4天| 3((3))
2 --> |数据库设计 2天| 4((4))
3 --> |后端开发 6天| 5((5))
4 --> |前端开发 5天| 6((6))
5 --> |集成测试 3天| 6
6 --> |用户验收测试 2天| 7((7))
style 1 fill:#lightblue,stroke:#333,stroke-width:2px
style 2 fill:#lightblue,stroke:#333,stroke-width:2px
style 3 fill:#lightblue,stroke:#333,stroke-width:2px
style 4 fill:#lightblue,stroke:#333,stroke-width:2px
style 5 fill:#lightblue,stroke:#333,stroke-width:2px
style 6 fill:#lightblue,stroke:#333,stroke-width:2px
style 7 fill:#lightblue,stroke:#333,stroke-width:2px
```