Linq查詢使用group by和having

Question

所以，我一直在嘗試復制這個SQL查詢：

select COUNT(*) as Total_2_Review
from (
    select processed_image_id, count(*) as Total_Confirm from dbo.history 
    where action_id=104
    group by processed_image_id
    having count(*) > 1
) as tbl

與Linq如下：

var total2Review = (from h in secondDb.Histories.Where(i => i.ActionId == 104)
                    group h by new { h.ActionId, h.ProcessedImageId } into g
                    where g.Key.ActionId > 1
                    select g).Count();

但是，我知道它應該是正確的，因為我沒有在我的組子句中選擇大於1的實際計數。

如何將此SQL查詢作為LINQ查詢來完成？

Answer 1

LINQ在Where和Having之間沒有區別。 將根據您的Where子句的位置生成適當的SQL查詢。

以下是我將SQL查詢轉換為LINQ的方法：

var total2Review = secondDb.Histories
    .Where(i => i.ActionId == 104) // This "Where" remains a "where"
    .GroupBy(i => i.ProcessedImageId)
    .Where(g => g.Count() > 1)     // This "Where" becomes "having"
    .Count();                      // This gets the overall count

Answer 2

在group by之后的where更改Key.ActionId .Count() ：

var total2Review = (from h in secondDb.Histories.Where(i => i.ActionId == 104)
                    group h by new { h.ActionId, h.ProcessedImageId } into g
                    where g.Count()> 1
                    select g).Count();