转换SQL查询LINQ

Question

我有一个表叫visit有以下栏目：

visit_Id 
member_Id 
visit_Date 
visit_Time 
visit_DateTime 
visit_Status values like (accepted, refused) 

我有以下SQL查询：

string sql = @"SELECT CONCAT(UPPER(SUBSTRING(visit_Status, 1, 1)), SUBSTRING(visit_Status FROM 2)) as Status, COUNT('x') AS Visits 
    FROM visits 
    WHERE visit_Date BETWEEN '2001-09-08' AND '2009-09-09' 
    GROUP BY visit_Status"; 

我如何转换这个SQL到LINQ？我的实体名称是dbcontext。预先感谢您的帮助。

Answer 1

您需要使用EntityFunctions

DateTime dateFrom = new DateTime(2001, 9, 8); 
DateTime dateTo = new DateTime(2001, 9, 9); 

var query = from v in dbcontext.Visits 
      where v.visit_Date >= dateFrom && v.visit_Date <= dateTo 
      group v by v.visit_Status into vg 
      select new 
      { 
       Status = EntityFunctions.Concat(EntityFunctions.ToUpper(vg.Key[0]), 
               EntityFunctions.SubString(1, EntityFunctions.Length(vg.Key) -1), 
       Visits = vg.Count() 
      } 

Answer 2

你能告诉我你在用Count（'x'）做什么吗？

from v in dbcontext.visits 
where v.visit_Date >= "2001-09-08" && v.visitDate <= "2009-09-09" 
group by v.visit_Status 
select new 
{ 
    Status = string.Concat(char.ToUpper(v.visit_Status[0], v.visit_Status.Substring(1)), 
    Visits = //Not sure what 'x' is in your example 
}