我正在尝试比较两个数据表并捕获第三个数据表中的差异。
DataTable one = new DataTable();
one.Columns.Add("ID");
one.Columns.Add("PCT");
one.Rows.Add("1", "0.1");
one.Rows.Add("2", "0.2");
one.Rows.Add("3", "0.3");
DataTable two = new DataTable();
two.Columns.Add("ID");
two.Columns.Add("PCT");
two.Columns.Add("OldPCT");
two.Rows.Add("1", "0.1", "0");
two.Rows.Add("2", "0.1", "0");
two.Rows.Add("3", "0.9", "0");
two.Columns.Remove("OldPCT");
//First method
DataTable three = two.AsEnumerable().Except(one.AsEnumerable()).CopyToDataTable();
foreach (DataRow dr in three.AsEnumerable())
{
string strID = dr[0].ToString();
string strPCT = dr[1].ToString();
}
//second method
var diffName = two.AsEnumerable().Select(r => r.Field<string>("PCT")).Except(one.AsEnumerable().Select(r => r.Field<string>("PCT")));
if (diffName.Any())
{
DataTable Table3 = (from row in two.AsEnumerable()
join name in diffName
on row.Field<string>("PCT") equals name
select row).CopyToDataTable();
}
到目前为止，我已经尝试了两种方法，但并没有达到预期的效果，应该是这样。
在第三个数据表中，值应如下所述。
ID PCT
2 O.1
3 0.9
最近一期：
DataTable one = new DataTable();
one.Columns.Add("ID");
one.Columns.Add("PCT");
one.Rows.Add("1", "0.1");
one.Rows.Add("2", "0.2");
one.Rows.Add("2", "0.2");
one.Rows.Add("3", "0.3");
one.Rows.Add("3", "0.3");
DataTable two = new DataTable();
two.Columns.Add("ID");
two.Columns.Add("PCT");
two.Rows.Add("1", "0.1");
two.Rows.Add("2", "0.1");
two.Rows.Add("2", "0.1");
two.Rows.Add("3", "0.8");
two.Rows.Add("3", "0.9");
现在，我需要从数据表中获取除第一行以外的所有行。但是我只得到最后三行。
基于Hogan的答案，可以将其DataRowComparer.Default用作方法的第二个参数Except()（而不是创建自定义IEqualityComparer）：
// this will get all rows from table two that don't match rows in one
// the result is an IEnumerable<DataRow>
var unmatched = two.AsEnumerable()
.Except(one.AsEnumerable(), DataRowComparer.Default);
// CopyToDataTable converts an IEnumerable<DataRow> into a DataTable
// but it blows up if the source object is empty
// this statement makes sure unmatched has data before calling CopyToDataTable()
// if it is empty, we 'clone' (make an empty copy) of one of the original DataTables
var three = unmatched.Any() ? unmatched.CopyToDataTable() : one.Clone();
这将对每行中的字段进行基于值的比较，以确定它们是否相等。
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