让我们说我有这个SQL语句:
SELECT p.ParentId,COUNT(c.ChildId)
从ParentTable p
LEFT OUTER JOIN ChildTable C对p.ParentId = c.ChildParentId
GROUP BY p.ParentId
我怎样才能把它理解的LINQ to SQL?我被困在COUNT(c.ChildId),生成的SQL似乎总是输出COUNT(*)。以下是我有这么远:
由对在context.ParentTable
加入c。在context.ChildTable上p.ParentId等于c.ChildParentId到J1
从J2在j1.DefaultIfEmpty()
一群J2通过p.ParentId到分组
选择新{的ParentId = grouped.Key,计数= grouped.Count()}
感谢您!
解决方案 由对在context.ParentTable
加入c。在context.ChildTable上p.ParentId等于c.ChildParentId到J1
从J2在j1.DefaultIfEmpty()
一群J2通过p.ParentId到分组
选择新{的ParentId = grouped.Key,计数= grouped.Count(T =>!t.ChildId = NULL)}
Let's say I have this SQL:
SELECT p.ParentId, COUNT(c.ChildId)
FROM ParentTable p
LEFT OUTER JOIN ChildTable c ON p.ParentId = c.ChildParentId
GROUP BY p.ParentId
How can I translate this into LINQ to SQL? I got stuck at the COUNT(c.ChildId), the generated SQL always seems to output COUNT(*). Here's what I got so far:
from p in context.ParentTable
join c in context.ChildTable on p.ParentId equals c.ChildParentId into j1
from j2 in j1.DefaultIfEmpty()
group j2 by p.ParentId into grouped
select new { ParentId = grouped.Key, Count = grouped.Count() }
Thank you!
解决方案from p in context.ParentTable
join c in context.ChildTable on p.ParentId equals c.ChildParentId into j1
from j2 in j1.DefaultIfEmpty()
group j2 by p.ParentId into grouped
select new { ParentId = grouped.Key, Count = grouped.Count(t=>t.ChildId != null) }