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  • [C#]DataTable常用操作总结

    【引言】项目中经常使用DataTable,发现有好多东西,需要整理下.
        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("            System.IO.TextReader trSchema = new System.IO.StringReader(xml.Substring(xml.IndexOf("            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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  • 原文地址:https://www.cnblogs.com/googlegis/p/2978994.html
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