[LINQ][DataSet] 依條件加總數量

 

decimal total = dt.AsEnumerable()
 .Sum(r => r.Field<decimal?>("Col1") ?? 0);

decimal? total = dt.AsEnumerable()
 .Sum(r => r.Field<decimal?>("Col1")); // use total.HasValue and total.Value

decimal d = 0;
decimal total = dt.AsEnumerable()
 .Where(r => decimal.TryParse(r.Field<string>("Col1"), out d))
 .Sum(r => d);

decimal total = dt.AsEnumerable()
 .Where(r => !r.IsNull("Col1") && decimal.TryParse(r["Col1"].ToString(), out d))
 .Sum(r => d);



ref web:
https://stackoverflow.com/questions/22294929/using-dt-asenumerable-sum-for-columns-having-string-null-value