For this test, the Ex versions of the strsafe functions set NULL on failure and 0xfe as the fill byte.

在测试中，调用ex版本的strsafe系列函数的程序会在调用失败时把缓冲区设为NULL，并以0xfe作为填充字节，代码如下。

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When ON delete set NULL is active, when a record is deleted from the parent table, all records in the child table with matching foreign key values are set to NULL.

当ON DELETE SET NULL规则被激活时，如果一条记录从父表中删除，子表中的所有记录以及匹配的外键值都被设置为NULL。

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The use of these specific columns ensures that the related column values are not inadvertently set to NULL.

这些特定列的使用能够确保相关的列值不会意外设置为NULL。

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