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问题描述
II有两个数据表如下
II have two data tables as follows
dtOne
-------------------------
ID | Name
--------------------------
101 | AA
102 | BB
103 | CC
104 | DD
105 | EE
106 | FF
--------------------------
dtTwo
-------------------------
ID | Name
--------------------------
101 | AA
102 | BBAA
103 | CCBB
104 | DD
107 | GG
108 | HH
--------------------------
我只想把结果作为'在dtOne`和'不在dtTwo`中的数据（dtOne-dtTwo）
I just want the result as data which is `in dtOne` and `not in dtTwo` (dtOne-dtTwo)
dtResult
-------------------------
ID | Name
--------------------------
101 | AA
102 | BB
103 | CC
104 | DD
107 | GG
108 | HH
105 | EE
106 | FF
--------------------------
我怎样才能实现这个目标。
我尝试过：
How can i achieve this .
What I have tried:
DataSet ds = new DataSet();
DataSet ds1 = new DataSet();
ds1.ReadXml(HttpContext.Current.Server.MapPath("XML/myFile.xml"));
DataTable dt1 = ds1.Tables[0];
var query = (from p in dt.AsEnumerable()
join t in dt1.AsEnumerable()
on p.Field<string>("Station") equals t.Field<string>("Station")
select new
{
Station = p.Field<string>("Station"),
Max_Temp = p.Field<string>("Max_Temp"),
Min_Temp = p.Field<string>("Min_Temp"),
Weather_Detail = p.Field<string>("Weather_Detail"),
DateTime = p.Field<string>("DateTime")
});
DataTable myDataTable = new DataTable();
myDataTable.Columns.Add("DateTime", typeof(string));
myDataTable.Columns.Add("Station", typeof(string));
myDataTable.Columns.Add("Max_Temp", typeof(string));
myDataTable.Columns.Add("Min_Temp", typeof(string));
myDataTable.Columns.Add("Weather_Detail", typeof(string));
foreach (var element in query)
{
var row = myDataTable.NewRow();
row["DateTime"] = element.DateTime;
row["Station"] = element.Station;
row["Max_Temp"] = element.Max_Temp;
row["Min_Temp"] = element.Min_Temp;
row["Weather_Detail"] = element.Weather_Detail;
myDataTable.Rows.Add(row);
}
DataTable dtExtraRow = new DataTable();
if ((dt1 != null && dt1.Rows.Count > 0) && (myDataTable != null && myDataTable.Rows.Count > 0))
{
var temp1 = dt1.Rows.OfType<datarow>().Where(a => dt1.Rows.OfType<datarow>().
Select(k => Convert.ToString(k["Station"])).Except(myDataTable.Rows.OfType<datarow>().Select(k => Convert.ToString(k["Station"])).ToList()).Contains(Convert.ToString(a["Station"]))).AsEnumerable();
if (temp1 != null && temp1.Count() > 0)
dtExtraRow = temp1.CopyToDataTable();
}
if (dtExtraRow.Rows.Count > 0)
myDataTable = myDataTable.AsEnumerable().Union(dtExtraRow.AsEnumerable(), DataRowComparer.Default).CopyToDataTable();
DataTable dtExtraRowOfXml = new DataTable();
if ((dt != null && dt.Rows.Count > 0) && (myDataTable != null && myDataTable.Rows.Count > 0))
{
var temp = dt.Rows.OfType<datarow>().Where(a => dt.Rows.OfType<datarow>().
Select(k => Convert.ToString(k["Station"])).Except(myDataTable.Rows.OfType<datarow>().Select(k => Convert.ToString(k["Station"])).ToList()).Contains(Convert.ToString(a["Station"]))).AsEnumerable();
if (temp != null && temp.Count() > 0)
dtExtraRowOfXml = temp.CopyToDataTable();
}
if (dtExtraRowOfXml.Rows.Count > 0)
myDataTable = myDataTable.AsEnumerable().Union(dtExtraRowOfXml.AsEnumerable(), DataRowComparer.Default).CopyToDataTable();
ds.Tables.Add(myDataTable);
string strXml = ds.GetXml();
XmlDocument xDoc = new XmlDocument();
xDoc.LoadXml(strXml);
xDoc.Save(HttpContext.Current.Server.MapPath("XML/myFile.xml")); //XML is the folder name and myFile.xml is ur new file name推荐答案
private void UpdateXml(DataTable dt1, DataTable dt2)
{
-------matching row should be updated and nomatching row should be added in dt2
DataTable Match = dt1.AsEnumerable().Where(ra => dt2.AsEnumerable().Any(rb => rb.Field<string>("Station") == ra.Field<string>("Station"))).AsDataView().ToTable();
foreach (DataRow dRNew in Match.Rows)
{
DataRow row = dt2.AsEnumerable().Where(r => r.Field<string>("Station").Equals(dRNew["Station"])).First();
row["DateTime"] = dRNew["DateTime"];
row["Station"] = dRNew["Station"];
row["Max_Temp"] = dRNew["Max_Temp"];
row["Min_Temp"] = dRNew["Min_Temp"];
row["Weather_Detail"] = dRNew["Weather_Detail"];
}
DataTable NoMatch = dt1.AsEnumerable().Where(ra => !dt2.AsEnumerable().Any(rb => rb.Field<string>("Station") == ra.Field<string>("Station"))).AsDataView().ToTable();
NoMatch.Merge(dt2);
//dt1.Merge(NoMatch);
NoMatch.DefaultView.Sort = "Station";
NoMatch = NoMatch.DefaultView.ToTable();
}
//get result list by using Union method together with IEqualityComparer
var result = dt1.AsEnumerable()
.Union(dt2.AsEnumerable(), new MyComparer())
.OrderBy(x=>x.Field<int>("ID"));</int>
比较器类的定义：
And the definition of comparer class:
public class MyComparer : IEqualityComparer<datarow>
{
// rows are equal if their ID are equal.
public bool Equals(DataRow x, DataRow y)
{
//Check whether the compared objects reference the same data.
if (Object.ReferenceEquals(x, y)) return true;
//Check whether any of the compared objects is null.
if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
return false;
//Check whether the rows are equal.
return x.Field<int>("ID") == y.Field<int>("ID");
}
// If Equals() returns true for a pair of objects
// then GetHashCode() must return the same value for these objects.
public int GetHashCode(DataRow dr)
{
//Check whether the object is null
if (Object.ReferenceEquals(dr, null)) return 0;
//Get hash code for the ID field.
return dr.Field<int>("ID").GetHashCode();
}
}</int></int></int></datarow>
结果：
Result:
ID Name
101 AA
102 BB
103 CC
104 DD
105 EE
106 FF
107 GG
108 HH
更多信息： []
您可能想要使用： []。
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