您可以添加计算列，当应该执行FK时，该列将为 0 ，否则为 NULL 。然后可以在外键引用中使用它：

You can add a computed column which will be 0 when the FK ought to be enforced and NULL otherwise. This can then be used in the foreign key reference:

Create Table Account (
  AccountId Int,
  Uniquifier Int,

  NomineeId Int,
  NomineeXRef as CASE WHEN Uniqueifier > 0 THEN 0 END persisted

  Constraint PK$Account Primary Key (AccountId, Uniquifier),
  Constraint FK$SelfReference Foreign Key (NomineeId,NomineeXRef) References Account (AccountId, Uniquifier)     
)