Linq to Sql的子查询

Question

我有以下的LINQ语句。我如何改变这个，所以我只在子查询中得到GroupID。 我的语法在这里不起作用。

而且也只有不同的用户。

from u in Users 
join ug in UserGroups on u.UserID equals ug.UserID 
where ug.GroupID == (from igr in UserGroups where igr.UserID == 1 select igr.GroupID) 
select u 

Answer 1

我会打破它成可读性两个单独的查询，但在这里不用

var group = from igr in UserGroup 
      where irg.UserID == 1 
      select igr.GroupID; 

var result = from u in Users 
       join ug in UserGroups on u.UserID equals ug.UersID 
       into x 
       where group.Contains(x.GroupID) 
       select x; 

作为一个查询，我相信它会像这样工作

var result = from u in Users 
       join ug in UserGroups on u.UserID equals ug.UersID 
       into x 
       where 
       (from igr in UserGroup 
       where irg.UserID == 1 
       select igr.GroupID).Contains(x.GroupID) 
       select x; 

Answer 2

这是怎么做的然后结束。

var query = (from u in _dbctx.Users 
    join ug in _dbctx.UserGroups on u.UserID equals ug.UserID 
    where _dbctx.UserGroups.Any(igr => igr.GroupID == ug.GroupID && igr.UserID == 1) 
    select GetUser(u)).Distinct(); 

Answer 3

from u in Users 
    join ug in UserGroups on u.UserID equals ug.UserID 
    where ug.GroupID == (from igr in UserGroups where igr.UserID == 1 select igr.GroupID).FirstOrDefault() 
    select u 

内查询必须恰好返回一个值