为什么我不能写两个条件？我该如何解决这个问题？

Question

List<MasterQuestion> questions = _sql.MasterQuestions
    .Include(x => x.MasterQuestionVariants)
    .Where(x => x.MasterQuestionExamId == ed.ExamMasterDetailExamId 
             && x.MasterQuestionSectorId == ed.ExamMasterDetailSectorId 
             && x.MasterQuestionSubjectId == 6 
             && x.MasterQuestionSubjectId == 7)
    .ToList();

我能得到两个或更多吗来自同一列的相等性

Answer 1

有几种方法可以做到这一点。对 MasterQuestionSubjectId 或 Contains 使用 || 运算符（即用 OR 代替 AND）。例如（注意额外的括号）：

List<MasterQuestion> questions = _sql.MasterQuestions
    .Include(x => x.MasterQuestionVariants)
    .Where(x => x.MasterQuestionExamId == ed.ExamMasterDetailExamId 
             && x.MasterQuestionSectorId == ed.ExamMasterDetailSectorId 
             && (x.MasterQuestionSubjectId == 6 || x.MasterQuestionSubjectId == 7))
    .ToList();

或者这个更具可读性和可扩展性，因为您可以向数组添加多个 ID，并且查询不会变得更难阅读：

var ids = new [] { 6, 7 };

List<MasterQuestion> questions = _sql.MasterQuestions
    .Include(x => x.MasterQuestionVariants)
    .Where(x => x.MasterQuestionExamId == ed.ExamMasterDetailExamId 
             && x.MasterQuestionSectorId == ed.ExamMasterDetailSectorId 
             && ids.Contains(x.MasterQuestionSubjectId))
    .ToList();

为什么我不能写两个条件？我该如何解决这个问题？

why can't I write two conditions ? how can I fix this problem?

linq

asp.net-core