[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("<?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();