Question

有没有办法检查PREM_A或PREM_B的总和在同一LINQ查询中是不是0，而不是在单独的LINQ查询中，如下面的那个，即matchRows？

var resultsDt = dt.AsEnumerable().GroupBy(row => new
{
    Id = row.Field<string>("ID")
}).Select(grp =>
{
    DataRow newRow = dt.NewRow();
    newRow["ID"] = grp.Key.Id.Trim();
    newRow["PREM_A"] = grp.Sum(r => r.Field<decimal>("PREM_A"));
    newRow["PREM_B"] = grp.Sum(r => r.Field<decimal>("PREM_B"));
    return newRow;
}).CopyToDataTable();

var matchRows = resultsDt.Select().Where(x => x.Field<decimal>("PREM_A") != 0 || x.Field<decimal>("PREM_B") != 0);
foreach (DataRow row in matchRows)
{
    //do something
}

Answer 1

您不需要为每一步转换为数据表，如果您离开它，将更容易查询。

var query =
    from row in dt.AsEnumerable()
    group new
    {
        premA = row.Field<decimal>("PREM_A"),
        premB = row.Field<decimal>("PREM_B"),
    } by row.Field<string>("ID").Trim() into g
    let premA = g.Sum(x => x.premA)
    let premB = g.Sum(x => x.premB)
    where premA != 0M || premB != 0M
    select new
    {
        Id = g.Key,
        PremA = premA,
        PremB = premB,
    };

Answer 2

此外：

 var resultsDt = dt.AsEnumerable()
                   .GroupBy(row => row.Field<string>("ID"))                       
                   .Select(grp =>new {Id= grp.Key,
                                     PREM_A= grp.Sum(r => r.Field<decimal>("PREM_A")),
                                     PREM_B=grp.Sum(r => r.Field<decimal>("PREM_B"))
                                     })
                   .Where(e=>e.PREM_A!=0 || e.PREM_B!=0);

C＃LINQ检查同一查询中的列总和

2 个答案: