Question

这是我想要运行的SQL：

DECLARE @StartDt DATETIME, @EndDt DATETIME
SET @StartDt='2009-01-01'
SET @EndDt='2010-06-01'

SELECT  
AVG(DATEDIFF(day, CreatedDt, CompletedDt)) 
AVG(DATEDIFF(day, CreatedDt, ComplianceDt)) 
FROM MyTable
WHERE RequestDt BETWEEN @StartDt AND @EndDt

这可以用Linq（C＃）表示并让它全部在数据库上运行吗？

Answer 1

DateTime startDt = new DateTime(2009, 1, 1);
DateTime endDt = new DateTme(2010, 6, 1);

var query = dc.MyTables
  .Where(x => startDt <= x.RequestDate && x.RequestDt <= endDt)
  .GroupBy(x => 1)  //unsure about this group by
  .Select(g => new
  {
    FirstAvg = g.Average(x =>
      SqlMethods.DateDiffDay(x.CreatedDt, x.CompletedDt)),
    SecondAvg = g.Average(x =>
      SqlMethods.DateDiffDay(x.CreatedDt, x.ComplianceDt))
  });

var row = query.Single();

如何在linq中编写此SQL平均查询

1 个答案: