Question

我有两个var变量数据类型，我想两者都具有并集。我该怎么办？

var results = from table1 in dtTimeListTable.AsEnumerable()
              join table2 in readyDataTable.AsEnumerable() on (decimal)table1["Avnr"] equals (int)table2["Avnr"]
              orderby table2["Substation"],  table2["S6_NAME"]
              select new
              {
                   Substation = (string)table2["Substation"],
                   S6_NAME = (string)table2["S6_NAME"],
                   ptime = ((DateTime)table1["DBTM"]).ToString("dd/MM/yyyy HH:mm").Substring(11, 5),
                   Wert = (decimal)table1["Wert"]
              };

var resultsMaxMin = from table1 in dtMaxMin.AsEnumerable()
              join table2 in readyDataTable.AsEnumerable() on (decimal)table1["Avnr"] equals (int)table2["Avnr"]
              orderby table2["Substation"], table2["S6_NAME"]
              select new
              {
                   Substation = (string)table2["Substation"],
                   S6_NAME = (string)table2["S6_NAME"],
                   ptime =table1["ptime"],
                   Wert = (decimal)table1["Wert"]
              };

Answer 1

此代码段可能会有所帮助：

            var list = new List<int>();

            var sublist1 = list.Select(x => new { foo = 1, bar = 2, baz = "baz" });
            var sublist2 = list.Select(x => new { bar = 3, foo = 1, baz = "baz" });
            var sublist3 = list.Select(x => new { foo = 3, bar = "a", baz = "baz" });
            var union1 = sublist1.Union(sublist2); // compilation error
            var union2 = sublist1.Union(sublist3); // compilation error

仅当匿名类型与字段的名称，排序和 type 完全匹配时，Union（）才起作用。如果在第二个选择中交换foo和bar的顺序，然后在第三个选择中将bar转换为int值，则代码段中的错误就会消失。

在您的示例中，ptime在两个列表之间的类型不同-字符串和对象。

两个var变量数据类型的并集

1 个答案: