# 案例：Type of Record in dual that is not a real table can not be shipped
#### 问题根因
优化器识别到的record列，且record列对应的主表不是一个实体表。最常见的情况为MERGE INTO语句的USING部分使用了FROM dual子句导致问题出现。
**处理方案**：改写SQL，消除语句中的dual子句。
#### 案例1：子查询f为(SELECT 0 AS inv_id,0 AS ovs_pack_num,0 AS ovs_pack_id FROM DUAL)
**原始语句**
```
MERGE INTO dwiscm.dwi_inv_balance_onhand t USING (
    SELECT
        f.inv_id,
        d.ovs_pack_id
    FROM (SELECT 0 AS inv_id,0 AS ovs_pack_num,0 AS ovs_pack_id FROM DUAL) f,
    dwicommon.dwi_inv_oversea_pack d
    WHERE f.ovs_pack_num = d.ovs_pack_num
) S ON (t.inv_id = s.inv_id)
WHEN MATCHED THEN UPDATE
SET t.ovs_pack_id = s.ovs_pack_id, t.last_upd_cycle_id = 20250301000000, t.dw_last_update_date = sysdate;
```
![](https://support.huaweicloud.com/devg-911-dws/figure/zh-cn_image_0000002526271425.png "点击放大")
**改写语句**
```
MERGE INTO dwiscm.dwi_inv_balance_onhand t USING (
    SELECT
        0 AS inv_id,
        d.ovs_pack_id
    FROM dwicommon.dwi_inv_oversea_pack d
    WHERE 0 = d.ovs_pack_num
) S ON (t.inv_id = s.inv_id)
WHEN MATCHED THEN UPDATE
SET t.ovs_pack_id = s.ovs_pack_id, t.last_upd_cycle_id = 20250301000000, t.dw_last_update_date = sysdate;
```
![](https://support.huaweicloud.com/devg-911-dws/figure/zh-cn_image_0000002526313205.png "点击放大")
**修改点对比**
![](https://support.huaweicloud.com/devg-911-dws/figure/zh-cn_image_0000002493993772.png "点击放大")