c# - Lambda表达式，其中ID在ID列表中

我有2个清单

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>();

如何获得questionId中listquestionold的答案：
listanswers =db.tblanswers.where(p=> p.ExamQuestionId exists in listquestionold吗？

最佳答案

使用Contains的List方法很容易：

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