Question

我会在多个条件下选择

我知道我可以选择使用这个陈述

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

但我想做类似的事情

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

但是无法识别和关键字

Answer 1

不要让查询语法欺骗你:) - 它是C＃，所以and仍然是&&：

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语法中更简洁地表达（如果使用带有谓词的FirstOrDefault overload，则可以删除冗余的Select和Where子句：

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();

Where和子句实体框架

2 个答案: