ASP. NET binding with Hierarchy drop-down box (select control)

1.

2. Data structure of tables in database

3. Front Page

    <id= "pid"  runat= "Server">        <  value= "0"  data= "|0|" > do not select parent class </option>    </Select >

Note: View source code

4. Backstage Code

using System; using System.Data; using System.Web.UI.WebControls;

// binding drop-down frame with hierarchy (select control)         Binddropdownlist (0"┗━""|0| ");

    /// <summary>    ///tie-down frame with layers/// </summary>    /// <param name= "Pitemid" >Parent class Number</param>    /// <param name= "Levelstr" >Hierarchy Style</param>    /// <param name= "Pitemvalue" >Level value</param>    protected voidBinddropdownlist (intPitemid,stringLEVELSTR,stringpitemvalue) {        //get a list of news categoriesDataTable dt = Express.BLL.NewsCategory.GetDataSet (). tables[0]; //determine if it is a parent class, change its level value        if(Pitemid! =0) {Levelstr+=string. IsNullOrEmpty (LEVELSTR)?"┗━":"┻━"; Pitemvalue + = Pitemid +"|"; }        //to iterate over a data item in a control's list control        foreach(DataRow DrinchDt. Select ("parentid="+Pitemid)) {            //initializing data items in a list controlListItem Li =NewListItem (); //set the text displayed for a data itemLi. Text = Levelstr + dr["ItemName"].            ToString (); //set the value associated with a data itemLi. Value = dr["Id"].            ToString (); //to add Data property values for an itemLi. Attributes.Add ("Data", Pitemvalue + li. Value +"|"); //append a data item to the control             This. PID.            Items.Add (LI); //traversing a subclass data item in a list control binddropdownlist (Convert.ToInt32 (li.        Value), Levelstr, pitemvalue); }    }

5. Database part

        /// <summary>        ///get all categories for which the name is not empty/// </summary>        /// <returns></returns>         PublicDataSet GetDataSet () {stringsql ="SELECT * from newscategory where itemname<> "ORDER by replace (Itemvalue,convert (varchar,id) + ' | ', '), Sortvalue"; returnSqlHelper.ExecuteDataset (connstring.connreadonly, CommandType.Text, SQL,NULL); }

Points of knowledge involved:

(1) binding data in a database to a drop-down box

<id= "pid"  runat= "Server">    <  value= "0"  data= "|0|" > do not select parent class </option></select> 

Method One:

  DataSet ds = Express.BLL.AdminLeft.GetDataSet ();   foreach  in DS. tables[0]. Rows)  {     pid. Items.Add (newListItem (dr["ItemName"). ToString (), dr["Id"]. ToString ()));  }

Note:

ListItem reference space: System.Web.UI.WebControls;

ListItem (string text,string value); /text refers to the literal displayed in ListItem; value refers to ListItem.

Method Two:

    Pid. DataSource = DT; // to set the data source    for a control " ItemName " // Set the text    displayed for a data item " Id "; // Set the value    associated with a data item Pid. DataBind (); // to bind data to a control

(2) "DataTable.Select method" return value: Array of DataRow objects

Dt. Select (filter condition);

Dt. Select ();

 

Dt. Select (filter criteria, sort);