SQL Server takes the latest record in a recent group

/*1 Use a subquery to filter out ParentID NULL*/Select *  fromBid_projectpackagealtereddesigninfo t0where exists(    Select 1  from    (        SelectParentID,Max(Altertime) asAltertime fromBid_projectpackagealtereddesigninfoGroup  byparentid) xwhereX.parentid=T0. ParentID andX.altertime=t0. Altertime)SelectA.*  fromBid_projectpackagealtereddesigninfo aInner Join (SelectParentID,Max(Altertime)'Altertime'   fromBid_projectpackagealtereddesigninfoGroup  byParentID) b onA.parentid=B.parentid andA.altertime=B.altertime/*You cannot filter out ParentID null.*/SelectA.*   fromBid_projectpackagealtereddesigninfo awhere  not exists (    Select 1  fromBid_projectpackagealtereddesigninfo bwhereB.parentid=A.parentid andB.altertime>a.altertime)/*2 Using Window functions*//*You cannot filter out ParentID null.*/Select *  from(SelectParentid,altertime,Max(Altertime) Over(Partition byParentID) asAltertimemax frombid_projectpackagealtereddesigninfo) xwhereAltertimemax=Altertime

SQL Server takes the latest record in a recent group