C# DataTable的用法详解

在项目中常常常使用到DataTable,假设DataTable使用得当，不仅能使程序简洁有用，并且可以提高性能，达到事半功倍的效果，现对DataTable的使用技巧进行一下总结。 

        一、DataTable简单介绍    

          (1)构造函数 

          DataTable()   不带参数初始化DataTable 类的新实例。 

          DataTable(string tableName)  用指定的表名初始化DataTable 类的新实例。 

          DataTable(string tableName, string tableNamespace) 用指定的表名和命名空间初始化DataTable类的新实例。 

          (2) 常常使用属性 

          CaseSensitive    指示表中的字符串比较是否区分大写和小写。 

          ChildRelations   获取此DataTable 的子关系的集合。 

          Columns             获取属于该表的列的集合。 

          Constraints        获取由该表维护的约束的集合。 

          DataSet               获取此表所属的DataSet。DataSet相关信息，可见我曾经的一篇文章《数据访问(2)－DataSet》 

          DefaultView       获取可能包含筛选视图或游标位置的表的自己定义视图。 

          HasErrors          获取一个值，该值指示该表所属的DataSet 的不论什么表的不论什么行中是否有错误。 

          MinimumCapacity  获取或设置该表最初的起始大小。该表中行的最初起始大小。默认值为 50。 

          Rows                  获取属于该表的行的集合。 

          TableName       获取或设置DataTable 的名称。 

          (3)常常使用解决方案 

          AcceptChanges()   提交自上次调用AcceptChanges() 以来对该表进行的全部更改。 

          BeginInit()         开始初始化在窗口上使用或由还有一个组件使用的DataTable。初始化发生在执行时。

          Clear()               清除全部数据的DataTable。 

          Clone()              克隆DataTable 的结构，包含全部DataTable 架构和约束。 

          EndInit()            结束在窗口上使用或由还有一个组件使用的DataTable 的初始化。初始化发生在执行时。 

          ImportRow(DataRow row)    将DataRow 拷贝到DataTable 中，保留不论什么属性设置以及初始值和当前值。 

          Merge(DataTable table)  将指定的DataTable 与当前的DataTable 合并。 

          NewRow()         创建与该表具有相同架构的新DataRow。

 

        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 假设没有赋值,则用is null来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

         //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; 

       （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

           //绑定的事实上是DefaultView

          gvTestDataTable.DataSource = dt;

          gvTestDataTable.DataBind();

         （13）judge the DataTable’s Column name is a string

          //推断一个字符串是否为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;

        }