DataTable常用操作分享

NetX行者 2011-10-13 10:26:51



protected void Page_Load(object sender, EventArgs e)

    {

        //①创建DataTable

        DataTable dt = new DataTable("Table_AX");



        //②为DataTable增加列

        //方法 1

        dt.Columns.Add("column0", System.Type.GetType("System.String"));

        //方法 2

        DataColumn dc = new DataColumn("column1", System.Type.GetType("System.Boolean"));

        dt.Columns.Add(dc);



        //③为 DataTable增加行

        //★增加初始化的行

        DataRow dr = dt.NewRow();

        dr["column0"] = "AX";

        dr["column1"] = true;

        dt.Rows.Add(dr);

        //★增加未初始化的行

        DataRow dr1 = dt.NewRow();

        dt.Rows.Add(dr1);



        //④查找

        //Search the second row 如果没有赋值,则用is null来select

        DataRow[] drs = dt.Select("column1 is null");

        DataRow[] drss = dt.Select("column0 = 'AX'");





        //⑤复制 DataTable 包括数据

        DataTable dtNew = dt.Copy();



        //⑥Copy DataTable only scheme

        DataTable dtOnlyScheme = dt.Clone();



        //⑦操作一行

        //★都是对dt的操作

        //方法1

        DataRow drOperate = dt.Rows[0];

        drOperate["column0"] = "AXzhz";

        drOperate["column1"] = false;

        //方法2

        drOperate[0] = "AXzhz";

        drOperate[1] = false;

        //方法3

        dt.Rows[0]["column0"] = "AXzhz";

        dt.Rows[0]["column1"] = false;

        //方法4

        dt.Rows[0][0] = "AXzhz";

        dt.Rows[0][1] = false;



        //⑧Evaluate another DataTable's row to current Datatable

        dtOnlyScheme.Rows.Add(dt.Rows[0].ItemArray);



        //⑨Use Rowstate

        //■■■■■■■■■■■■■■■■■■■■■■■■■■■■

        //不知道怎么才能使Row的State变为DataRowState.Deleted

        //More further,怎样设置Row的State

        //■■■■■■■■■■■■■■■■■■■■■■■■■■■■

        if (dt.Rows[0].RowState == DataRowState.Unchanged)

        {

            //Your logic

        }



        //⑩Convert to string

        System.IO.StringWriter sw = new System.IO.StringWriter();

        System.Xml.XmlTextWriter xw = new System.Xml.XmlTextWriter(sw);

        dt.WriteXml(xw);

        string s = sw.ToString();



        //ⅰ.string convert to DataTable【Doesn't achieve it】

        //■■■■■■■■■■■■■■■■■■■■■■■■■■■■

        //没有把string成功转换为DataTable        ■■已实现,参见追加■■

        //■■■■■■■■■■■■■■■■■■■■■■■■■■■■

        //DataTable dtConvert = new DataTable();

        //System.IO.StringReader stream = new System.IO.StringReader(s);

        //System.Xml.XmlReader xtr = new System.Xml.XmlTextReader(stream);

        //dtConvert.ReadXml(xtr);



        //ⅱ.Filter DataTable

        //It's so strange that the second row has been filtered

        //the second row show in GridView never

        //It means null field will be filter always.

        //Filter the all conditions

        dt.DefaultView.RowFilter = "column1 <> true";

        //dt.DefaultView.RowFilter = "column1 = true";



        dt.DefaultView.RowStateFilter = DataViewRowState.Added;



        //ⅲ.Sort row

        //Stupid method

        DataRow[] drsss = dt.Select(String.Empty, "column0 DESC , column1 ASC");

        //Clever method

        dt.DefaultView.Sort = "column0 , column1 ASC";



        //ⅳ.Bind DataTable

        //绑定的其实是DefaultView

        gvTestDataTable.DataSource = dt;

        gvTestDataTable.DataBind();

    }



 



【追加】判断一个字符串是否为DataTable的列名



dtInfo.Columns.Contains("AX");



 



【追加】DataTable与XML的转换



       protected void Page_Load(object sender, EventArgs e)

        {

            DataTable dt_AX = new DataTable();



            //dt_AX.Columns.Add("Sex", typeof(System.Boolean));

            //DataRow dr = dt_AX.NewRow();

            //dr["Sex"] = true;

            //dt_AX.Rows.Add(dr);



            string xml=ConvertBetweenDataTableAndXML_AX(dt_AX);

            DataTable dt = ConvertBetweenDataTableAndXML_AX(xml);

        }



        public string ConvertBetweenDataTableAndXML_AX(DataTable dtNeedCoveret)

        {

            System.IO.TextWriter tw = new System.IO.StringWriter();

            //if TableName is empty, WriteXml() will throw Exception.

            dtNeedCoveret.TableName=dtNeedCoveret.TableName.Length==0?"Table_AX":dtNeedCoveret.TableName;

            dtNeedCoveret.WriteXml(tw);

            dtNeedCoveret.WriteXmlSchema(tw);

            return tw.ToString();

        }



        public DataTable ConvertBetweenDataTableAndXML_AX(string xml)

        {

            System.IO.TextReader trDataTable = new System.IO.StringReader(xml.Substring(0, xml.IndexOf("<?xml")));

            System.IO.TextReader trSchema = new System.IO.StringReader(xml.Substring(xml.IndexOf("<?xml")));

            DataTable dtReturn = new DataTable();

            dtReturn.ReadXmlSchema(trSchema);

            dtReturn.ReadXml(trDataTable);

            return dtReturn;

        }



 



【追加】排序的好方法



            dt.DefaultView.Sort = "ID ,Name ASC";

            dt=dt.DefaultView.ToTable();