Question

我有以下SQL脚本，它给了我之后的结果，我无法复制完整的连接，并且活动计数的计数不同：

   select ActivityCount,ActivityComplete, ImagePath, SubjectTitle from
(select 
Count(Distinct(Act.[ActivityID])) as ActivityCount,
Sum(Case when (([OutcomeID] = 1 or [OutcomeID] = 3) and AOU.ActivityUserID=1 ) Then 1 Else 0 End) As ActivityComplete,
Sub.[SubjectImageName] as ImagePath,
Sub.SubjectTitle as SubjectTitle
from [dbo].[UserActivityOutcome] AOU
full join Activity Act on Act.[ActivityID] = AOU.[ActivityID]
left join Category Cat on Act.[CategoryID] = Cat.[CategoryID]
left join Subject Sub on Cat.[SubjectID] = Sub.[SubjectID]
group by Sub.SubjectTitle,  Sub.[SubjectImageName]
) as x

结果：

</head>
<body><div class="spacer"><table id="t1"><tr><td class="typeheader" colspan="4">Result Set (2 items)</td></tr><tr><th title="System.Int32">ActivityCount</th><th title="System.Int32">ActivityComplete</th><th title="System.String">ImagePath</th><th title="System.String">SubjectTitle</th></tr><tr><td class="n">25</td><td class="n">3</td><td>Subject 1.png</td><td>Subject 1</td></tr><tr><td class="n">1</td><td class="n">1</td><td>Subject 2.png</td><td>Subject 2</td></tr><tr><td title="Total=26&#xD;&#xA;Average=13" class="columntotal">26</td><td title="Total=4&#xD;&#xA;Average=2" class="columntotal">4</td><td title="Totals" class="columntotal"></td><td title="Totals" class="columntotal"></td></tr></table></div></body>
</html>

我的linq看起来像这样：

 from x in (
    (from Act in Activities 
    join AOU in UserActivityOutcomes on Act.ActivityID equals AOU.ActivityID  into AOU_join
    from AOU in AOU_join.DefaultIfEmpty()
    join ActNA in Activities on AOU.ActivityID equals ActNA.ActivityID into ActNA_join
    from ActNA in ActNA_join.DefaultIfEmpty()
    join Cat in Categories on AOU.Activity.CategoryID equals Cat.CategoryID into Cat_join
    from Cat in Cat_join.DefaultIfEmpty()
    join Sub in Subjects on Cat.SubjectID equals Sub.SubjectID into Sub_join
    from Sub in Sub_join.DefaultIfEmpty()
    group new {Sub, AOU, Act,ActNA} by new {
      Sub.SubjectTitle,
      Sub.SubjectImageName
    } into g
    select new {
      ActivityCount =  g.Distinct().Count(), //g.Count(),
      ActivityComplete = g.Sum(p => (
      (p.AOU.OutcomeID == 1 ||
      p.AOU.OutcomeID == 3)&&
      p.AOU.ActivityUserID == 23 ? 1 : 0)),
      ImagePath = g.Key.SubjectImageName,
      SubjectTitle = g.Key.SubjectTitle
    }))
select new {
  x.ActivityCount,
  x.ActivityComplete,
  x.ImagePath,
  x.SubjectTitle
}

Answer 1

LINQ full outer join很棘手。可以模拟的唯一方法是left outer join和right antijoin的联合。这是IMO LINQ等同于您的SQL查询：

var query =
    // AOU full join Act
    (from e in (from AOU in UserActivityOutcomes
                join Act in Activities on AOU.ActivityID equals Act.ActivityID into Act_join
                from Act in Act_join.DefaultIfEmpty()
                select new { AOU, Act })
               .Concat
               (from Act in Activities
                join AOU in UserActivityOutcomes on Act.ActivityID equals AOU.ActivityID into AOU_join
                from AOU in AOU_join.DefaultIfEmpty()
                where AOU == null
                select new { AOU, Act })
     let AOU = e.AOU
     let Act = e.Act
     // left join Cat
     join Cat in Categories on Act.CategoryID equals Cat.CategoryID into Cat_join
     from Cat in Cat_join.DefaultIfEmpty()
     // left join Sub
     join Sub in Subjects on Cat.SubjectID equals Sub.SubjectID into Sub_join
     from Sub in Sub_join.DefaultIfEmpty()

     group new { Sub, AOU, Act } by new { Sub.SubjectTitle, Sub.SubjectImageName } into g
     select new
     {
         ActivityCount = g.Where(e => e.Act != null).Select(e => e.Act.ActivityID).Distinct().Count(),
         ActivityComplete = g.Sum(e => (e.AOU.OutcomeID == 1 || e.AOU.OutcomeID == 3) && e.AOU.ActivityUserID == 1 ? 1 : 0),
         ImagePath = g.Key.SubjectImageName,
         SubjectTitle = g.Key.SubjectTitle
    };

Linq To实体没有完全加入问题

1 个答案: