学步园

//首先要添加System.Data.DataSetExtensions;
DataSet ds = new DataSet();

ds.Locale = CultureInfo.InvariantCulture;

FillDataSet(ds);
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 intersection of the two tables. 求交集用 Intersect/Union(并集)/Except(差集)
var contacts = contacts1.AsEnumerable().Intersect(contacts2.AsEnumerable(),

                                                    DataRowComparer.Default);
Console.WriteLine("Intersection of contacts tables");
foreach (DataRow row in contacts)

{

    Console.WriteLine("Id: {0} {1} {2} {3}",

        row["ContactID"], row["Title"], row["FirstName"], row["LastName"]);

}

 上面为MSDN的代码，下面为自己的代码，相对简洁些：

DbHelperSQL.connectionString = strSiteConnection;
DataTable dtblSiteTable = DbHelperSQL.TQuery("Select * From " + strTableName);
IEnumerable<DataRow> querySite = from contact in dtblSiteTable.AsEnumerable() select contact;
DbHelperSQL.connectionString = strMainConnection;
DataTable dtblMainTable = DbHelperSQL.TQuery("Select * From " + strTableName);
IEnumerable<DataRow> queryMain = from contact in dtblMainTable.AsEnumerable() select contact;
var EnumerableExcept = querySite.CopyToDataTable().AsEnumerable().Except(queryMain.CopyToDataTable().AsEnumerable(), DataRowComparer.Default);
 
DataTable dtblExcept = EnumerableExcept.CopyToDataTable();  //dtblExcept 即为差异的数据表