dataTable (zhuan)

 protected void Page_Load(object sender, EventArgs e)
    {
        //①Create a DataTable
        DataTable dt = new DataTable("Table_AX");

        //②Add columns for DataTable
        //Method 1
        dt.Columns.Add("column0", System.Type.GetType("System.String"));
        //Method 2
        DataColumn dc = new DataColumn("column1", System.Type.GetType("System.Boolean"));
        dt.Columns.Add(dc);

        //③Add rows for DataTable
        //★Initialize the row
        DataRow dr = dt.NewRow();
        dr["column0"] = "AX";
        dr["column1"] = true;
        dt.Rows.Add(dr);
        //★Doesn't initialize the row
        DataRow dr1 = dt.NewRow();
        dt.Rows.Add(dr1);

        //④Select row
        //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'");

        //⑤Copy DataTable include data
        DataTable dtNew = dt.Copy();

        //⑥Copy DataTable only scheme
        DataTable dtOnlyScheme = dt.Clone();

        //⑦Operate one row
        //★都是对dt的操作
        //Method 1
        DataRow drOperate = dt.Rows[0];
        drOperate["column0"] = "AXzhz";
        drOperate["column1"] = false;
        //Method 2
        drOperate[0] = "AXzhz";
        drOperate[1] = false;
        //Method 3
        dt.Rows[0]["column0"] = "AXzhz";
        dt.Rows[0]["column1"] = false;
        //Method 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();

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