在項目中經經常使用到DataTable,假設DataTable使用得當，不僅能使程序簡潔有用，并且可以提高性能，達到事半功倍的效果，現對DataTable的使用技巧進行一下總結。?
??????? 一、DataTable簡單介紹????
??????????(1)構造函數?
??????????DataTable()?? 不帶參數初始化DataTable 類的新實例。?
??????????DataTable(string tableName)? 用指定的表名初始化DataTable 類的新實例。?
??????????DataTable(string tableName, string tableNamespace) 用指定的表名和命名空間初始化DataTable 類的新實例。?
??????????(2) 經常使用屬性?
??????????CaseSensitive??? 指示表中的字符串比較是否區分大寫和小寫。?
??????????ChildRelations?? 獲取此DataTable 的子關系的集合。?
??????????Columns???????????? 獲取屬于該表的列的集合。?
??????????Constraints??????? 獲取由該表維護的約束的集合。?
??????????DataSet?????????????? 獲取此表所屬的DataSet。?
??????????DefaultView?????? 獲取可能包含篩選視圖或游標位置的表的自己定義視圖。?
??????????HasErrors????????? 獲取一個值，該值指示該表所屬的DataSet 的不論什么表的不論什么行中是否有錯誤。?
??????????MinimumCapacity? 獲取或設置該表最初的起始大小。該表中行的最初起始大小。默認值為 50。?
??????????Rows????????????????? 獲取屬于該表的行的集合。?
??????????TableName?????? 獲取或設置DataTable 的名稱。?
??????????(3)經常用法?
??????????AcceptChanges()?? 提交自上次調用AcceptChanges() 以來對該表進行的全部更改。?
??????????BeginInit()???????? 開始初始化在窗口上使用或由還有一個組件使用的DataTable。初始化發生在執行時。
??????????Clear()?????????????? 清除全部數據的DataTable。?
??????????Clone()????????????? 克隆DataTable 的結構，包含全部DataTable 架構和約束。?
??????????EndInit()??????????? 結束在窗口上使用或由還有一個組件使用的DataTable 的初始化。初始化發生在執行時。?
??????????ImportRow(DataRow row)??? 將DataRow 拷貝到DataTable 中，保留不論什么屬性設置以及初始值和當前值。?
??????????Merge(DataTable table)? 將指定的DataTable 與當前的DataTable 合并。?
??????????NewRow()???????? 創建與該表具有同樣架構的新DataRow。
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??????? 二、DataTable使用技巧
????? （1）Create a DataTable
???????? DataTable dt = new DataTable("Table_AX");?
????? （2）Add 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);?
?????? （3）Add 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);??
??????? （4）Select row
???????? //Search the second row 假設沒有賦值,則用is null來select
???????? DataRow[] drs = dt.Select("column1 is null");
???????? DataRow[] drss = dt.Select("column0 = 'AX'");?
??????? （5）Copy DataTable include data
???????? DataTable dtNew = dt.Copy();?
??????? （6）Copy DataTable only scheme
???????? DataTable dtOnlyScheme = dt.Clone();?
??????? （7）Operate one row
???????? //對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;?
?????? （8）Evaluate another DataTable's row to current Datatable
???????? dtOnlyScheme.Rows.Add(dt.Rows[0].ItemArray);?
?????? （9）Convert 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();
??????? （10）Filter DataTable
???????? dt.DefaultView.RowFilter = "column1 <> true";
???????? dt.DefaultView.RowFilter = "column1 = true";
??????? （11）Sort row
????????? dt.DefaultView.Sort = "ID ,Name ASC";
????????? dt=dt.DefaultView.ToTable();
???????? （12）Bind DataTable
?????????? //綁定的事實上是DefaultView
????????? gvTestDataTable.DataSource = dt;
????????? gvTestDataTable.DataBind();
???????? （13）judge the DataTable’s Column name is a string
????????? //推斷一個字符串是否為DataTable的列名
???????? dtInfo.Columns.Contains("AX");
???????? （14）DataTable convert to XML and XML convert to DataTable
????????? 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;
??????? }
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