如何去掉DataTable中的重复行(新增.net 2.0中最新解决方法---简便)

.net 1.1中的解决方法(转)
1建立一个DataSetHelper类(DataSetHelper.cs)

public class DataSetHelper
...{
    public DataSet ds;
    public DataSetHelper(ref DataSet DataSet)
    ...{
        ds = DataSet;
    }
    public DataSetHelper()
    ...{
        ds = null;
    }
    private bool ColumnEqual(object A, object B)
    ...{
        if (A == DBNull.Value && B == DBNull.Value) //  both are DBNull.Value
            return true;
        if (A == DBNull.Value || B == DBNull.Value) //  only one is DBNull.Value
            return false;
        return (A.Equals(B));  // value type standard comparison
    }
    public DataTable SelectDistinct(string TableName, DataTable SourceTable, string FieldName)
    ...{
        DataTable dt = new DataTable(TableName);
        dt.Columns.Add(FieldName, SourceTable.Columns[FieldName].DataType);

        object LastValue = null;
        foreach (DataRow dr in SourceTable.Select("", FieldName))
        ...{
            if (LastValue == null || !(ColumnEqual(LastValue, dr[FieldName])))
            ...{
                LastValue = dr[FieldName];
                dt.Rows.Add(new object[] ...{ LastValue });
            }
        }
        if (ds != null)
            ds.Tables.Add(dt);
        return dt;
    }
}

2 建立一个Web窗体，在page_load中写下面的代码

       DataSet ds;
        DataSetHelper dsHelper;
        ds = new DataSet();
        dsHelper = new DataSetHelper(ref ds);

        // Create source table
        DataTable dt = new DataTable("Orders");
        dt.Columns.Add("EmployeeID", Type.GetType("System.String"));
        dt.Columns.Add("OrderID", Type.GetType("System.Int32"));
        dt.Columns.Add("Amount", Type.GetType("System.Decimal"));

        dt.Rows.Add(new object[] ...{ "Sam", 5, 25.00 });
        dt.Rows.Add(new object[] ...{ "Tom", 7, 50.00 });
        dt.Rows.Add(new object[] ...{ "Sue", 9, 11.00 });
        dt.Rows.Add(new Object[] ...{ "Tom", 12, 7.00 });
        dt.Rows.Add(new Object[] ...{ "Sam", 14, 512.00 });
        dt.Rows.Add(new Object[] ...{ "Sue", 15, 17.00 });
        dt.Rows.Add(new Object[] ...{ "Sue", 22, 2.50 });
        dt.Rows.Add(new object[] ...{ "Tom", 24, 3.00 });
        dt.Rows.Add(new object[] ...{ "Tom", 33, 78.75 });

        ds.Tables.Add(dt);
       DataTable td=dsHelper.SelectDistinct("DistinctEmployees", ds.Tables["Orders"], "EmployeeID");
       this.GridView1.DataSource = td;
       this.GridView1.DataBind();

 .net 2.0中的解决方法(原创)

public DataTable GetTopSearch()
        {
            DataSet dsKeyword = dal.GetKeyword();
            DataSet dsTopSearch = new DataSet();
            for (int i = 0; i < 4; i++)
            {
                string keyword = dsKeyword.Tables[0].Rows[i]["Name"].ToString();
                string condition = dsKeyword.Tables[0].Rows[i]["SearchCondition"].ToString();
                dsTopSearch.Merge(dal.GetTopSearch(keyword,condition));
            }
            return dsTopSearch.Tables[0].DefaultView.ToTable(true, "ID","Name","Author","Publisher","PublishDate","TypeName","Price","SalePrice","SavePrice","Rebate","ImagePath","ContentIntro");
        }

先把DataTable转成DataView,再通过DataView.ToTable()转回DataTable,ToTable()方法中有一个重载可以轻松消除重复行.
注:该重载的第二个参数为要保存的字段名.