c# - 使用 LINQ 将两个不同类型的 IQueryable 变量连接在一起

Question

列名称和类型相同，但它来自两个不同的实体。这是一个简化的示例:

--Query View
var v_res = from s in db.V_CMUCUSTOMER
           select s;

--Values from table less values from view
var res = from s in db.CMUCUSTOMERs
          where !(from v in v_res
            select v.ID).Contains(s.ID)
         select s;

--join table and view values into one variable
var res_v_res = (from c in res
            select c).Union(from v in v_res
            select v);

但是我收到以下错误:

实例参数:无法从“System.Linq.IQueryable”转换为 System.Linq.ParallelQuery

Answer 1

如果您指定一个新的匿名类型并为两者使用 ToList()，那么您应该能够按如下方式联合它们:

var v_res = (from s in db.V_CMUCUSTOMER
            select new { custName = s.customer_name custAddress = s.address}).ToList();

--Values from table less values from view
var res = (from s in db.CMUCUSTOMERs
          where !(from v in v_res
            select v.ID).Contains(s.ID)
          select new { custName = s.customer_name custAddress = s.address }).ToList();

--join table and view values into one variable
var res_v_res = v_res.Union(res);

如果有几十列，这可能会很麻烦，但应该仍然有效。