DataTable常用操作总结
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();