Asp. NET and database related skills-Basic application

first, get the value of data table I row J column

To establish and open a database connection
OleDbConnection conn=new OleDbConnection ();
Conn. Connectionstring=strconnectionstring;//strconnectionstring a database connection string
Conn. Open ();

String Sql= "SELECT * from Newsclass ORDER by ClassId Desc";
string x;
DataSet ds=new DataSet ();
OleDbDataAdapter da=new OleDbDataAdapter (sql,conn);
Da. Fill (ds, "newstable");
DataTable Dt=ds. tables["Newstable"];
X=dt. ROWS[I][1]. ToString ()//data Table I row J column value
Conn.close ();


Ii. read the data into the DropDownList

(1) Add data in DropDownList

To establish and open a database connection
OleDbConnection conn=new OleDbConnection ();
Conn. Connectionstring=strconnectionstring;//strconnectionstring a database connection string
Conn. Open ();

String Sql= "SELECT * from Newsclass ORDER by ClassId Desc";
Set up a dataset
DataSet ds=new DataSet ();
OleDbDataAdapter da=new OleDbDataAdapter (sql,conn);
Da. Fill (ds, "newstable");
This. Dropdownlist1.datasource=ds;
This. Dropdownlist1.datatextfield = "ClassName";//text value
This. Dropdownlist1.datavaluefield = "ClassID";//value value
This. Dropdownlist1.databind ();

Conn. Close ();

(2) Select one of the DropDownList

This. DropDownList1.Items.FindByValue (dr["ClassID"). ToString (). Trim ()). SELECTED=TRUE;//DR for DataRow

third, the classification of the code to retrieve the corresponding category name and display in the DataGrid

(1). Code in ASPX (ClassID is a classified encoding):

<asp:templatecolumn headertext= "category" >
<ItemTemplate>
<asp:label id=lblclass runat= "server" text= ' <%# getclassname (Convert.ToInt32 (DataBinder.Eval, " Dataitem.classid "))%> ' >
</asp:Label>
</ItemTemplate>
</asp:TemplateColumn>

(2) C # code:

<summary>
The category column returns text based on the number
</summary>
<param name= "ispassed" ></param>
<returns></returns>
public string getclassname (int ClassID)
{
OleDbConnection conn=new OleDbConnection ();
Conn. connectionstring=strconnectionstring;
Conn. Open ();

String Sql= "select * from Newsclass where classid=" +CLASSID;
DataSet ds=new DataSet ();
OleDbDataAdapter da=new OleDbDataAdapter (sql,conn);
Da. Fill (ds, "classtable");
DataTable Dt=ds. tables["Classtable"];
String Strclassname=dt. rows[0]["ClassName"]. ToString ();
Conn. Close ();

Return strclassname;//returns the classid corresponding classname
}