WHERE和条款实体框架

Question

我将取决于多个条件选择

我知道我可以使用此语句

var session = (from us in context.UserSessions 
       where us.UserId == dbUser.Id 
       select us).FirstOrDefault(); 

选择，但我想这样做

var session = (from us in context.UserSessions 
       where us.UserId == dbUser.Id 
       and us.somefield == somevalue 
       select us).FirstOrDefault(); 

但关键字不被识别

Answer 1

不要让查询语法骗了:) - 这是C＃，所以and仍然&&：

var session = (from us in context.UserSessions 
      where us.UserId == dbUser.Id 
      && us.somefield == somevalue 
      select us).FirstOrDefault(); 

或者，这可以在lambda语法更简洁表达（你可以删除冗余Select和Where条款，如果您使用FirstOrDefault overload这需要一个谓语）：

var session = context 
     .UserSessions 
     .FirstOrDefault(us => us.UserId == dbUser.Id && us.somefield == somevalue); 

Answer 2

var session = (from us in context.UserSessions 
       where us.UserId == dbUser.Id 
       && us.somefield == somevalue 
       select us).FirstOrDefault();