How to Bind dropdown list from code behind with data from database.

Question

Dear All,

                 I want to populate a dropdownlist from database in code behind. I tried with the following code but while binding it is throwing an error "Object Reference not set to an Instance". Please find the code appended.Thanks in advance.

Code:

Sample.aspx:

    <asp:DropDownList ID="ddlSample" runat="server" CssClass="textbox" Width="38%"></asp:DropDownList>

Sample.aspx.cs

System.Data.SqlClient.SqlConnection conn = null;
                SqlDataReader drFailureCode = null;
                string sqlQuery = string.Empty;

System.Data.SqlClient.SqlConnection conn = null;
                SqlDataReader drFailureCode = null;
                string sqlQuery = string.Empty;
                sqlQuery = "select distinct * from <tablename>";
                conn = SqlHelperConnection.getConnection();
                drFailureCode = SqlHelper.ExecuteReader(conn, CommandType.Text, sqlQuery);

                if (drFailureCode.HasRows)
                {
                    ddlSample.DataSource = drFailureCode;
                    ddlSample.DataTextField = "FailureID";
                    ddlSample.DataValueField = "FailureName";
                    ddlSample.DataBind();
                }
                drFailureCode.Close();
                ddlSample.Items.Insert(0, new ListItem("--Select--", "0"));

Thanks In Advance.

Sukesh Marla · Answer

I copied your code and created a sample code, Just Replaced Sql Helper with common SqlCommand and its working fine... U just try by that way and by that you may get reason for the actual error. Hope It Helped. Please Check This is Currect Answer .

Naresh Avari · Answer

Hi Vijay, Can you use the following sample: string query = string.Empty; query = "SELECT * FROM Categories"; using (SqlConnection con = new SqlConnection(connStr)) { con.Open(); using (SqlCommand cmd = new SqlCommand("SELECT * FROM Categories", con)) { using (SqlDataReader dr = cmd.ExecuteReader()) { while (dr.Read()) { ListItem li = new ListItem(); li.Value = dr["CategoryId"].ToString(); li.Text = dr["CategoryImage"].ToString(); ddlCategory.Items.Add(li); } } } }

Sukesh Marla · Answer

There was someting written inside sqlhelper or may be some issue with something else, I can help u but i have to take a look at you code, So share that as zip if you can.

vijay rags · Answer

Hi, I already shared the code.Beyond this I can't. Hope you understand. Any alternate solution will be helpful.

Sukesh Marla · Answer

Can u share code...i check and revert back...

vijay rags · Answer

Hi, Thanks for your reply. I am getting the list of values but while binding only it is throwing error (i.e., ddlSample.DataSource line.)Whether we need to set any properties for DropDownList.

Sukesh Marla · Answer

It was some issue with SQLHelper calsses. Hope It Helped. Please Check This is Currect Answer .

How to Bind dropdown list from code behind with data from database.

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