DataTable usage tips

Protected void Page_Load (object sender, EventArgs e)
{
// 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. If no value is assigned, use is null to 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 ();

// 7operate one row
//★All operations on dt
// 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;

// Perform Evaluate another DataTable's row to current Datatable
DtOnlyScheme. Rows. Add (dt. Rows [0]. ItemArray );

// Use Rowstate
// ■
// Do not know how to change the Row State to DataRowState. Deleted
// More further, how to set the Row State
// ■
If (dt. Rows [0]. RowState = DataRowState. Unchanged)
{
// Your logic
}

// 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 ();

// I. string convert to DataTable [Doesn't achieve it]
// ■
// The string is not successfully converted to the DataTable ■ implemented, see Append ■
// ■
// 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
// Bind the defaview View
GvTestDataTable. DataSource = dt;
GvTestDataTable. DataBind ();
}
[Append] determines whether a string is the column name of the DataTable.
DtInfo. Columns. Contains ("AX ");
[Append] DataTable and XML Conversion
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;
} [Append] A Good sorting method
Dt. DefaultView. Sort = "ID, Name ASC ";
Dt = dt. DefaultView. ToTable ();

This article from the CSDN blog, reproduced please indicate the source: http://blog.csdn.net/jbgh608/archive/2007/10/29/1854686.aspx