Question

这是我的加入：

var jCorsi = from t in db.Table1
             join j in db.Table2 on t.IDCourse equals j.IDCourse
             select new { t, j };

我需要（稍后使用其他查询）才能使用两个表的字段。例如：

var testx = (from j in jCorsi
             group j by j.IDCourse  into g

但它说“找不到j.IDCourse的定义”，即使我选择了t和j。

我哪里错了？

Answer 1

你应该做

var testx = (from j in jCorsi
             group j by j.t.IDCourse  into g
             select ...

（j.t.代替j.）

也许最好让它更明确：

var jCorsi = from t in db.Table1
             join j in db.Table2 on t.IDCourse equals j.IDCourse
             select new { Table1 = t, Table2 = j };

var testx = (from x in jCorsi
             group x by x.Table1.IDCourse  into g
             select ...

Answer 2

    var jCorsi = from t in table1
                 join j in table2 on t.IDCourse equals j.IDCourse
                 select new { t, j };

    var testx = from j in jCorsi
                group j by j.t.IDCourse into g
                select g;

如何选择我稍后可以与其他查询一起使用的联接中的所有字段？

2 个答案: