# sql: database is closed

- **ID:** `go/sql-connection-pool-timeout`
- **Domain:** go
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

在调用db.Close()后继续使用数据库连接

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.17 | active | — | — |

## Workarounds

1. **** (90% success)
   ```
   使用sync.Once确保Close只调用一次
   ```
2. **** (80% success)
   ```
   在应用生命周期结束时才关闭数据库
   ```

## Dead Ends

- **** — 未同步可能导致多个连接实例 (60% fail)
- **** — 导致后续操作全部失败 (90% fail)