order byが複数で、NULLを含む並び順の数字を得る

order by kana, Bxx
の並び順を更新する方法

Update AX Set col = A1.AX From
( select count(*) As CNT from XX A2
Left Join cust_m B2 On A2.Bid=B2.Bid
Where A1.Aid=A2.Aid And IsNull(B2.kana,0) < IsNull(B1.kana,1)
And B2.Bxx < B1.Bxx )
Left Join BX B2 On A2.Bid=B2.Bid