sqlserver 递归查询

WITH parent as(
select CONVERT(nvarchar,row_number() OVER (ORDER BY p.PARENT_ACTIVITY_ID ASC)) as seq,CONVERT(nvarchar,'    |') as prefix,p.* from Project.TT_ACTIVITY p where p.PARENT_ACTIVITY_ID is null and p.TT_BASE_PROJECT_ID=5169 
UNION all
select CONVERT(nvarchar,p1.seq+'.'+CONVERT(nvarchar,row_number() OVER (ORDER BY c.PARENT_ACTIVITY_ID ASC))),'    |'+p1.prefix),c.* from PROJECT.TT_ACTIVITY c inner join parent p1 on c.PARENT_ACTIVITY_ID=p1.TT_ACTIVITY_ID 
)
select seq,prefix+'--'+CONVERT(nvarchar,TT_ACTIVITY_ID) as tree,PARENT_ACTIVITY_ID parentId,NAME,CODE from parent order by seq asc;