c# - 使用 Lambda 表达式加入和分组

Question

查询

 var grpby4 = from u in dtEmp.AsEnumerable()
                         join v in dtDept.AsEnumerable() on u.Field<int>("DepartmentID") equals v.Field<int>("DepartmentID")
                         group u by v.Field<string>("DeptName") into g
                         select new { DeptName = g.Key, Records = g };

如何使用 Lambda 表达式编写相同的查询？

Answer 1

使用 this handy webpage我明白了

dtEmp.AsEnumerable()
    .Join(dtDept.AsEnumerable(),
        u => u.Field<int>("DepartmentID"),
        v => v.Field<int>("DepartmentID"),
        (u, v) => new { u, v })
    .GroupBy(τ0 => τ0.v.Field<string>("DeptName"), τ0 => τ0.u)
    .Select(g => new { DeptName = g.Key, Records = g })