sql 时间向减函数

  select datediff(d, 

( select  isnull( ( select v.VerifyDate  from   T_VerifySituation v where OrderId = 19116 and  v.VerifyStatus= 1008 ),getdate()))

  ,

 (select v.VerifyDate  from   T_VerifySituation v where OrderId = 19116 and  v.VerifyStatus= 3024)

 )