LINQ To DataSet 設定運算子－Andrew的部落格

1.Distinct

a.get datatable

IEnumerable<DataRow> query = (from c in contact.AsEnumerable()
select c).Take(100);

DataTable contactsTableWith100Rows = query.CopyToDataTable();

b.use Distinct operator

List<DataRow> rows = new List<DataRow>();

//加入重覆的 datarows 資料
foreach (DataRow row in contactsTableWith100Rows.Rows)
    rows.Add(row);

// Create duplicate rows by adding the same 100 rows to the list.
foreach (DataRow row in contactsTableWith100Rows.Rows)
    rows.Add(row);

DataTable table =
    System.Data.DataTableExtensions.CopyToDataTable<DataRow>(rows);

IEnumerable<DataRow> uniqueContacts =
table.AsEnumerable().Distinct(DataRowComparer.Default);

2.Except

傳回在第一份資料表中出現但沒有在第二份資料表中出現的連絡人

DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds); //the function set dataadpter to dataset

DataTable contactTable = ds.Tables["Contact"];

// Create two tables.
IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("Title") == "Ms."
                              select contact;

IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("FirstName") == "Sandra"
                              select contact;

DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();

// Find the contacts that are in the first
// table but not the second.
var contacts = contacts1.AsEnumerable().Except(contacts2.AsEnumerable(),
                                               DataRowComparer.Default);

3.Intersect

傳回在這兩份資料表中都出現的連絡人

  IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("Title") == "Ms."
                              select contact;

IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("FirstName") == "Sandra"
                              select contact;

DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();

// Find the intersection of the two tables.
var contacts = contacts1.AsEnumerable().Intersect(contacts2.AsEnumerable(),
                                                    DataRowComparer.Default);

4.Union

傳回在其中一份資料表中出現的唯一連絡人

DataTable contactTable = ds.Tables["Contact"];
IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("Title") == "Ms."
                              select contact;

IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
                              where contact.Field<string>("FirstName") == "Sandra"
                              select contact;

DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();

// Find the union of the two tables.
var contacts = contacts1.AsEnumerable().Union(contacts2.AsEnumerable(),
                                                DataRowComparer.Default);