MERGE与FOREIGN KEY约束冲突

我有此更新脚本，其中将新数据加载到数据库中或更新现有数据.但是我得到了这些错误.

I've this updatescript in which I load new data into my db or update existing data. But I get these errors.

The MERGE statement conflicted with the FOREIGN KEY constraint
"FK_JW_MaterialData2PL_cMat_MaterialText". 
 The conflict occurred in database "TEST", table "dbo.JW_MaterialData", column 'camosGUID'.

和

The MERGE statement conflicted with the FOREIGN KEY constraint
"FK_JW_MaterialData_cMat_Material". The conflict occurred in 
database "TEST", table "dbo.cMat_Material", column 'camosGUID'.

这是相关的陈述.但是，当然还有更多的MERGE语句和更多的表.

This are the statements which are relevant. But of course there are a lot more MERGE statements with a lot more tables.

MERGE INTO [dbo].[JW_MaterialData2PL] ON camosGUID
WHEN MATCHED THEN UPDATE SET 
WHEN NOT MATCHED THEN INSERT 

MERGE INTO [dbo].[cMat_Material] ON camosGUID
WHEN MATCHED THEN UPDATE SET 
WHEN NOT MATCHED THEN INSERT 

MERGE INTO [dbo].[JW_MaterialData] ON camosGUID
WHEN MATCHED THEN UPDATE SET 
WHEN NOT MATCHED THEN INSERT 

FK_JW_MaterialData2PL_cMat_MaterialText和FK_JW_MaterialData_cMat_Material设置为ON UPDATE CASCADE和ON DELETE CASCADE.

也许这是我放入MERGE语句的顺序的问题吗?还是您知道可能是什么原因?

Maybe is this a problem of the order I put the MERGE statements? Or do you know what could be the reason?

另一个问题:当我再次运行脚本时，没有错误.那么只运行两次scipt可以吗，否则将来可能会引起问题吗?

And another question: When I run the script again there are no errors. So is it OK to just run the scipt twice or could this cause problems in the future?