如何使用LAMBDA表达式在LINQ中执行IN或CONTAINS？

Question

我有以下Transact-Sql,我试图转换为LINQ ...并挣扎.

SELECT * FROM Project
WHERE Project.ProjectId IN (SELECT ProjectId FROM ProjectMember Where MemberId = 'a45bd16d-9be0-421b-b5bf-143d334c8155')

任何帮助将不胜感激......如果可能的话,我想用Lambda表达式来做.

提前致谢!

Answer 1

GFrizzle打败了我.但这是一个C#版本

var projectsMemberWorkedOn = from p in Projects
                    join projectMember in ProjectMembers on
                        p.ProjectId equals projectMember.ProjectId
                    where projectMember.MemberId == "a45bd16d-9be0-421b-b5bf-143d334c8155"
                    select p;

作为一个纯粹的LINQ方法链版本的奖励:

var projectsMemberWorkedOn =
            Projects.Join( ProjectMembers, p => p.ProjectId, projectMember => projectMember.ProjectId,
                ( p, projectMember ) => new { p, projectMember } )
                .Where( @t => @t.projectMember.MemberId == "a45bd16d-9be0-421b-b5bf-143d334c8155" )
                .Select(@t => @t.p );

Answer 2

在这种情况下,您可以使用.Contains(),如下所示:

var projects = 
from p in db.Projects
where db.ProjectMembers.Where(m => m.MemberId == "a45bd16d-9be0-421b-b5bf-143d334c8155").Select(pp => pp.ProjectID).Contains(p.ProjectID)
select p;