在 LINQ 中计算多个列

Question

我知道这个问题的最佳答案是更好和优化的数据库，但是否可以在当前结构上优化这个总和？

表格是这样的：

rowid a1 b1 b2 b3
123   s  s  n  s
124   n  n  n  n
125   s  n  s  s

我需要计算所有“s”的个数。

var items = AsDynamic(App.Data["items"]).Where(p => Convert.ToDateTime(p.data).Year == ano);

var items_1a = items.Where(u => u.udd == "_1a");

var items_1a_jan = items_1a.Where(m => Convert.ToDateTime(m.data).Month == 1);

int items_1a_jan_s = items_1a_jan.Count(q => q.a1 == "s") + items_1a_jan.Count(q => q.b1 == "s") + items_1a_jan.Count(q => q.b2 == "s") + items_1a_jan.Count(q => q.b3 == "s") + items_1a_jan.Count(q => q.b4 == "s") + items_1a_jan.Count(q => q.b5 == "s") + items_1a_jan.Count(q => q.b6 == "s") + items_1a_jan.Count(q => q.b7 == "s") + items_1a_jan.Count(q => q.b8 == "s") + items_1a_jan.Count(q => q.b9 == "s") + items_1a_jan.Count(q => q.b10 == "s") + items_1a_jan.Count(q => q.b11 == "s") + items_1a_jan.Count(q => q.b12 == "s") + items_1a_jan.Count(q => q.b13 == "s") + items_1a_jan.Count(q => q.c1 == "s") + items_1a_jan.Count(q => q.c2 == "s") + items_1a_jan.Count(q => q.c3 == "s") + items_1a_jan.Count(q => q.c4 == "s") + items_1a_jan.Count(q => q.c5 == "s") + items_1a_jan.Count(q => q.c6 == "s") + items_1a_jan.Count(q => q.c7 == "s") + items_1a_jan.Count(q => q.c8 == "s") + items_1a_jan.Count(q => q.c9 == "s") + items_1a_jan.Count(q => q.c10 == "s") + items_1a_jan.Count(q => q.c11 == "s") + items_1a_jan.Count(q => q.c12 == "s") + items_1a_jan.Count(q => q.c13 == "s") + items_1a_jan.Count(q => q.c14 == "s") + items_1a_jan.Count(q => q.c15 == "s") + items_1a_jan.Count(q => q.c16 == "s") + items_1a_jan.Count(q => q.c17 == "s") + items_1a_jan.Count(q => q.d1 == "s") + items_1a_jan.Count(q => q.d2 == "s") + items_1a_jan.Count(q => q.d3 == "s") + items_1a_jan.Count(q => q.d4 == "s") + items_1a_jan.Count(q => q.d5 == "s") + items_1a_jan.Count(q => q.d6 == "s") + items_1a_jan.Count(q => q.d7 == "s") + items_1a_jan.Count(q => q.d8 == "s") + items_1a_jan.Count(q => q.d9 == "s") + items_1a_jan.Count(q => q.e1 == "s") + items_1a_jan.Count(q => q.e2 == "s") + items_1a_jan.Count(q => q.e3 == "s") + items_1a_jan.Count(q => q.e4 == "s") + items_1a_jan.Count(q => q.e5 == "s") + items_1a_jan.Count(q => q.e6 == "s") + items_1a_jan.Count(q => q.e7 == "s") + items_1a_jan.Count(q => q.e8 == "s") + items_1a_jan.Count(q => q.e9 == "s") + items_1a_jan.Count(q => q.e10 == "s") + items_1a_jan.Count(q => q.e11 == "s");

Answer 1

使用SelectMany 将每一行的列展平为一个长列表：

var result = items.SelectMany(i=> new string[] {i.a1, i.b1, i.b2, i.b3 })
                  .Count(i => i == "s");

Answer 2

如果你真的有这么多领域并且需要在所有领域中计数，那么你可以使用反射：

var sCount = data
    .Sum(x => x.GetType().GetProperties().Count(prop => prop.GetValue(x) as string == "s"));

Answer 3

我不确定您存储数据的确切方式，但您可以执行以下操作：

var rows =
        new []
        {
            new { RowNumber = 123, Chars = new Char[] { 's', 's', 'n', 's' } },
            new { RowNumber = 123, Chars = new Char[] { 'n', 'n', 'n', 'n' } },
            new { RowNumber = 123, Chars = new Char[] { 's', 'n', 's', 's' } }
        };

    var count =
        rows
            .SelectMany(row => row.Chars)
            .Count(chr => chr == 's');