sql怎么转换成linq

[toploveall]

select UserInfoID,UserName,NickName,Email 
from User_Info
 where UserInfoID in
 (
	select UserInfoID 
	from User_Classroom_R r 
	 where r.ClassroomInfoID in
	 ( 
		select ClassroomInfoID 
		from Classroom_Info
		where UserInfoID=1 
	 )
 )

select UserName,count(UserName) from User_Info
where UserName like 'z%'
group by UserName

关于以上两个sql语句，怎么转换成linq。谢谢。

[toploveall]

有没有什么转换工具

[threenewbee]

var query = from x
        in User_Info
        let query2 = 
            from r
            in User_Classroom_R
            let query3 = 
                Classroom_Info.Where(y => y.UserInfoID == 1).Select(y => y.ClassroomInfoID)
            where query3.Contains(r.ClassroomInfoID)
            select r.UserInfoID 
         where query2.Contains(x.UserInfoID)
         select new { x.UserInfoID, x.UserName, x.NickName, x.Email };

[threenewbee]

var query = from x in User_Info
            where UserName.StartsWith("z")
            group x by x.UserName into g
            select new { UserName = g.Key, Count = x.Count() };

[IE11下面经常卡到爆]

第一个
var result = from user in db.UserInfos
             where (from r in db.User_Classroom_R
                    where db.Classroom_Info.Any(ri => ri.ClassroomInfoID == r.ClassroomInfoID && ri.ClassroomInfoID == 1)
                    select r).Any(r => r.UserInfoID == user.UserInfoID)
             select user;

括号中的可以写成子查询，延迟执行的
第二个
var result = from user in db.Users
             where user.UserName.StartsWith("z")
             group user by user.UserName into g
             select new {g.Key, g.Count()};