# 错误：sql：结果集已关闭

- **ID:** `go/database-sql-rows-iteration-error-after-close`
- **领域:** go
- **类别:** data_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

在结果集关闭后尝试迭代，通常由于过早调用 defer row.Close() 或重复迭代。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 1.20 | active | — | — |
| 1.21 | active | — | — |

## 解决方案

1. **Defer rows.Close() after checking error and before iteration, but ensure iteration completes before close** (95% 成功率)
   ```
   rows, err := db.QueryContext(ctx, query)
if err != nil { return err }
defer rows.Close()
for rows.Next() { /* process */ }
if err = rows.Err(); err != nil { return err }
   ```

## 无效尝试

- **Calling rows.Close() at beginning of function** — Deferring Close before iteration closes rows prematurely, causing 'Rows are closed' error on Next(). (90% 失败率)