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  • DataTable的属性与使用方式

    一、DataTable简介    

    (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) 常用属性 
              CaseSensitive    指示表中的字符串比较是否区分大小写。 
              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。 
              DefaultView       获取可能包括筛选视图或游标位置的表的自定义视图。 
              HasErrors          获取一个值,该值指示该表所属的DataSet 的任何表的任何行中是否有错误。 
              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)常用方法 
              AcceptChanges()   提交自上次调用AcceptChanges() 以来对该表进行的所有更改。 
              BeginInit()         开始初始化在窗体上使用或由另一个组件使用的DataTable。初始化发生在运行时。

              Clear()               清除所有数据的DataTable。 
              Clone()              克隆DataTable 的结构,包括所有DataTable 架构和约束。 
              EndInit()            结束在窗体上使用或由另一个组件使用的DataTable 的初始化。初始化发生在运行时。 
              ImportRow(DataRow row)    将DataRow 复制到DataTable 中,保留任何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)创建DataTable
             DataTable dt = new DataTable("Table_AX"); 

    (2)给 DataTable 添加列
            //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)给 DataTable 添加行
             //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)选择行
             //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)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
               //绑定的其实是DefaultView
              gvTestDataTable.DataSource = dt;
              gvTestDataTable.DataBind();

    (13)judge the DataTable’s Column name is a string
              //判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;
            }

      (15)遍历

                   DataTable dt = new DataTable();

            string connectionString = ConfigurationManager.ConnectionStrings["local"].ToString();

            SqlConnection connectionObj = new SqlConnection(connectionString);
            connectionObj.Open();

            string sql = "select * from Users";
            SqlDataAdapter da = new SqlDataAdapter(sql, connectionObj);

            da.Fill(dt);

            int cols = dt.Columns.Count;
            int rows = dt.Rows.Count;

            for (int i = 0; i < rows; i++)
            {
              for (int j = 0; j < cols; j++)
              {
                HtmlString text = new HtmlString("<Label>第" + i + "行" + "第" + j + "列的内容是:" + dt.Rows[i][j].ToString() + "</label>              <br/>");
                label1.Text += text;
               }
             }

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  • 原文地址:https://www.cnblogs.com/leon719/p/3935654.html
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