ADO.net如何使用C＃和连接的模型在页面加载时将特定数据库表单元格中的数据绑定到转发器控件上？

Question

I want to bind the data from an oracle database cell to a bunch of labels within a repeater control, using C#, ADO.NET and the connected model. The display page repeater goes something like this (this is just one eval for simplicity):

<asp:Repeater ID="rptMain" runat="server" >
   <ItemTemplate>
     <h3 id="contactUs"> <%#Eval("ppCustSurvey")%> %></h3>
   </ItemTemplate>
</asp:Repeater>

Now the property string "ppCustSurvey" is a property that in my property class called ppContent. In my code behind page I have this as part of the page load

if (!Page.IsPostBack)
{
    clsContent objCon = new clsContent();
    rptMain.DataSource = objCon.getContent();
    rptMain.DataBind();
}

And the getContent() method points to this

public class clsContent
{
    static readonly string _strConn;

    static clsContent()
    {
        _strConn = WebConfigurationManager.ConnectionStrings["MyDilbert_Nov30"].ConnectionString;
    }
    public List<ppContent> getContent()
    {
        List<ppContent> objAllContent = new List<ppContent>();
        OracleConnection conn = new OracleConnection(_strConn);
        try
        {
            conn.Open();
            string strCmd = "Select site_content from content";
            OracleCommand cmd = new OracleCommand(strCmd, conn);
            OracleDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                ppContent objCon = new ppContent();
                objCon.ppCustSurvey = (dr["site_content"].ToString());
            }
            return objAllContent;
        }
        catch(Exception)
        {
            objAllContent.Clear();
            return objAllContent;
        }
        finally{
            conn.Close();
        }
    }
}

Now I think that I need to pass the parameter of the id of the column in order to identify ppCustSurvey as belonging to the column with the PK of 1. How do I do this?

Answer 1

I will post my solution for anyone who finds it useful. I solved the issue by adding this code to my class:

    public List<ppControls> getControls(int _id)
{
    List<ppControls> objAllControls = new List<ppControls>();
    OracleConnection conn = new OracleConnection(_strConn);
    OracleCommand cmd = new OracleCommand("SELECT * FROM controls WHERE reference =: parID", conn);
    cmd.Parameters.AddWithValue(":parID", _id);
    try
    {
        conn.Open();
        //string strCmd = parSelect;
        //OracleCommand cmd = new OracleCommand(strCmd, conn);
        OracleDataReader dr = cmd.ExecuteReader();
        while (dr.Read())
        {                objCon.ppCustSurvey = dr["controls_content"].ToString();}
        return objAllControls;
    }

Then in the code behind I pass the parameter of the foreign key like this

        rptMain.DataSource = objCon.getControls(7);
        rptMain.DataBind();

This is done for each repeater. I created a properties class with a get and set for ppCustSurvey, and assigned the property name to the Eval function of the repeater on the display page. Anyhow, that's how I solved it. Now I am curious about what way you would do this to lessen the hammering on the server, but that's a topic for another question.

Answer 2

If you are going to be gathering a lot of data from the database into a series of labels like this, I suspect that your DBAs could question the repeated hammering on the database (ie opening a connection and performing the select statement for each label each time the page is rendered), especially if this is a high-traffic site.

In cases like this, we usually fetch all of the necessary data from the database in one fell swoop and dynamically generate the required HTML in code-behind. This might take a little more work up front, but it should be much faster and have a lot less impact on the database.

If you want to stick with the current design, we would need to see how the PK for the column is defined in the client side, but it could be as easy as just adding a parameter to your ppCustSurvey method.