c# - Lambda 表达式，其中 id 在 id 列表中

Question

我有 2 个列表

var listquestionold = db.tblExamQuetions.Where(p => p.QuetionExamId == oldexamid).ToList();
var listquestionnew = listquestionnew = db.tblExamQuetions.Where(p => p.QuetionExamId == examid ).ToList();
List<tblExamQuestionAnswers> listanswers = new List<tblExamQuestionAnswers>();

如果 questionId 在 listquestionold 中，我如何获得答案:listanswers =db.tblanswers.where(p=> p.ExamQuestionId 存在于 listquestionold 中 ?

Answer 1

使用 Contains 很容易List 的方法:

var listquestionold = db.tblExamQuetions.Where(p => p.QuetionExamId == oldexamid).ToList();
var listanswers = db.tblanswers.Where(w => listquestionold.Contains(w.ExamQuestionId)).ToList();