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.