问题描述
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) }
解决方法
假设我有以下SQL:
SELECT p.ParentId,COUNT(c.ChildId)
FROM ParentTable p
LEFT OUTER JOIN ChildTable c ON p.ParentId = c.ChildParentId
GROUP BY p.ParentId
如何将其转换为LINQ to SQL?我被困在COUNT(c.ChildId),生成的SQL似乎总是输出COUNT(*)。这是到目前为止我得到的:
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() }
谢谢!