如果只需要一个连接器"，每个程序集ID排，您可以使用子查询进行过滤.假设 PartRefID 是唯一键:

If you want just one "connector" row per assembly ID, you can filter with a subquery. Assuming that PartRefID is a unique key:

select *
from parts as p
where [PartRefID] = (
    select max(p1.[PartRefID])
    from parts as p1
    where p1.[AssemblyID] = p.[AssemblyID] and p1.[PartDefID] = 2
)