将C＃Linq转换为T-Sql

Question

我是一名初级开发人员，尝试将以下linq语句转换为T-Sql：

    var results = context
      .Employees
      .Where(item => (dateFilter.ToUpper() == "P") ? item.PublishedDate >= From : item.CapturedDate >= dateFromDT)
      .Where(item => (dateFilter.ToUpper() == "P") ? item.PublishedDate <= dateTo : item.CapturedDate <= dateTo)
      .FirstOrDefault()

可以帮我吗？

Select * from Employees where PublishedDate = From and .......

Answer 1

我认为应该是这样。

 Select Top 1 * from Employees 
     where 
(dateFilter = "P" COLLATE Latin1_General_CS_AS  AND PublishedDate >= From AND PublishedDate >=dateTo) 
OR 
(dateFilter != "P" COLLATE Latin1_General_CS_AS AND CapturedDate  >= dateFromDT AND CapturedDate  >= dateTo)

Answer 2

您可以使用类似于以下内容的方法：

select top 1 * 
  from employees 
 where (upper(DateFilter) = 'P' and PublishedDate >= From and PublishedDate <= dateTo)
    or (upper(DateFilter) <> 'P' and CapturedDate >= dateFromDT and CapturedDate <= dateTo)

如果DateFilter是表中的一列，则最好跳过上面的那一列，因为它会降低性能（假设该列上有索引）。