SQL Server - 使用DISTINCT进行内部联接

Question

我很难做到以下几点:

select a.FirstName, a.LastName, v.District
from AddTbl a order by Firstname
inner join (select distinct LastName from
            ValTbl v  where a.LastName = v.LastName)  

我想在ValTbl上进行连接,但仅针对不同的值.

Answer 1

试试这个:

select distinct a.FirstName, a.LastName, v.District
from AddTbl a 
  inner join ValTbl v
  on a.LastName = v.LastName
order by a.FirstName;

或者这个(它做的相同,但语法不同):

select distinct a.FirstName, a.LastName, v.District
from AddTbl a, ValTbl v
where a.LastName = v.LastName
order by a.FirstName;

Answer 2

Nate，我认为您实际上为问题中的正确答案提供了一个良好的开端（您只需要正确的语法）。我也有同样的问题，将DISTINCT放在子查询中确实比这里提出的其他答案要便宜。

select a.FirstName, a.LastName, v.District
from AddTbl a 
inner join (select distinct LastName, District 
    from ValTbl) v
   on a.LastName = v.LastName
order by Firstname