Something wrong with C# dropdown list

timothy.farrell

I can't seem to get my dropdown list to populate. Webform: Code Behind: void ddl_DataBind() { SqlConnection SqlConn = new SqlConnection("server=c099450d01;uid=sa;pwd=;database=Tools"); SqlCommand SqlCmd = new SqlCommand("SELECT UID, LastName, FirstName FROM Employee ORDER BY LastName", SqlConn); SqlConn.Open(); ddl.DataSource = SqlCmd.ExecuteReader(CommandBehavior.CloseConnection); ddl.DataTextField = "LastName,FirstName"; ddl.DataValueField = "UID"; ddl.DataBind(); } I don't get any errors, just that the dropdown list doesn't contain any data. Thanks again for all your help. Sincerely, Tim

11 Replies

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timothy.farrell22y ago
New discovery!!! I just found out what the real problem (or additional problem) with this issue is. If you are hard coding a control(as I am) and attempt to modify the properties of the control via the GUI on the right hand side, then the control fails to populate. There are no generated errors either. I don't know if this is a bug or not in VS but if anyone has encountered this or knows of this issue feel free to speak up. Just thought you otta know. Tim
timothy.farrell22y ago
For some reason I feel like I'm submitting to my very own forum with one member (me). I wanted to let you all know that I have solved this issue. Wow. I could hear the applause from here. ;) Anyway, here is what I did. I started off my testing my code for the listbox control in a new webform page all by itself to see if there wasn't something else with my page that was causing the problem. I was estatic to see my listbox control fully populated. I then continued to add the rest of my controls one by one until the entire page was rebuilt. I have finished the rebuild and the page builds and browses without error. The only difference between the two pages was that I had a single control miss-named. The control id was UserKeywordSearch and the protected stmt in the code behind was referencing KeywordSearch. I don't know if that could have caused the problem with my listbox control or not but that was all I could find different between the two pages. Perhaps if someone out there can clarify the impact of this finding it may help others including myself. Thank you all for your patience and help!!!! Sincerely, Tim
timothy.farrell22y ago
Ok, so I tried working with the previous code last night only to still have the same problems. I have since gone back to a version of Mike's code in an effort to resolve the issue (and because it makes more sense to me). I have made a few minor additions to the code from the readings I have been scrutinizing over since last night: private void Page_Load(object sender, System.EventArgs e) { if (!IsPostBack) { SqlConnection SqlCon = new SqlConnection("server=C099450d01;uid=sa;pwd=;database=Tools"); SqlCon.Open(); DataSet ds = new DataSet(); SqlDataAdapter myDataAdapter; myDataAdapter = new SqlDataAdapter("SELECT UID, LastName + ', ' + FirstName AS Name FROM Employee ORDER BY LastName","server=C099450d01;uid=sa;pwd=;database=Tools"); myDataAdapter.Fill(ds, "Employee"); ddl.DataSource = ds.Tables["Employee"].DefaultView; ddl.DataTextField = "Name"; ddl.DataValueField = "UID"; ddl.DataBind(); SqlCon.Close(); } } Here is the listbox control: I am figuring that the response drop off since yesterday is due to either one of two reasons: 1. I am doing really stupid here and everyone is just waiting for me to catch the error or 2. No one has ever databound a listbox control before in C#. I tend to think that the first one is correct. Thank you all for your help. Sincerely, Tim
timothy.farrell22y ago
I found another link with some information concerning this: http://www.c-sharpcorner.com/Code/2003/July/DropDownListBox.asp Here is the modified code I am using. Once again, no data in the listbox, and no errors. SqlConnection mycn; SqlDataAdapter myda; DataSet ds; String strConn; private void Page_Load(object sender, System.EventArgs e) { if (!IsPostBack) { strConn="Data Source=C099450d01;uid=sa;pwd=;Initial Catalog=Tools"; mycn = new SqlConnection(strConn); myda = new SqlDataAdapter ("SELECT UID, LastName + ', ' + FirstName AS Name FROM Employee ORDER BY LastName ", mycn); ds = new DataSet(); myda.Fill (ds,"Table"); ddl.DataSource =ds.Tables [0] ; ddl.DataTextField =ds.Tables[0].Columns["Name"].ColumnName.ToString(); ddl.DataValueField =ds.Tables[0].Columns["UID"].ColumnName.ToString(); ddl.DataBind () ; } } I can't believe I've spent a day on trying to get one control to populate. Populating my datagrid only took a few minutes. Thank you for any help you may be able to provide. Sincerely, Tim
timothy.farrell22y ago
Mike, I did try it to no avial. Still no records. No Errors either. Checked View/Source as well in case there was an embedded error. This is really bizaar. Thank you again. Tim
miker22y ago
Tim, Did you try it? Did it work? If not, did you get any errors?
timothy.farrell22y ago
Mike, I'm sure I butchered this but I'm not familiar with using datatables to populate listboxes. Am I on the right track? void ddl_DataBind() { DataSet myDataSet = new DataSet(); SqlDataAdapter myDataAdapter; myDataAdapter = new SqlDataAdapter("SELECT UID, LastName + ', ' + FirstName AS Name FROM Employee ORDER BY LastName", "server=C099450d01;databaseTools;uid=sa;pwd=;"); myDataAdapter.Fill(myDataSet, "Employee"); SqlConn.Open(); ddl.DataSource = myDataSet.Tables["Employee"]; ddl.DataTextField = "Name"; ddl.DataValueField = "UID"; ddl.DataBind(); } Thank you for hanging in there with me. Sincerely, Tim
miker22y ago
Sorry, I did not read your code through. I think your problem here is in using SqlDataReader as a DataSource for dropDownList. Use DataTable instead.
timothy.farrell22y ago
Mike (or others), I am able to execute the query in Sql's QueryAnalyzer without issue but can't seem to get the listbox to populate. Is there anything wrong with the listbox control? Here is the code behind: void ddl_DataBind() { SqlConnection SqlConn = new SqlConnection("server=C099450d01;uid=sa;pwd=;database=Tools"); SqlCommand SqlCmd = new SqlCommand("SELECT UID, LastName + ', ' + FirstName AS Name FROM Employee ORDER BY LastName", SqlConn); SqlConn.Open(); ddl.DataSource = SqlCmd.ExecuteReader(CommandBehavior.CloseConnection); ddl.DataTextField = "Name"; ddl.DataValueField = "UID"; ddl.DataBind(); } Thank you for your thoughts. Regards, Tim
timothy.farrell22y ago
Mike, Thank you for your time. I have implemented your code however, I still get no records. Any additional thoughts? Sincerely, Tim
miker22y ago
void ddl_DataBind() { SqlConnection SqlConn = new SqlConnection("server=c099450d01;uid=sa;pwd=;database=Tools"); SqlCommand SqlCmd = new SqlCommand("SELECT UID, LastName + ', ' + FirstName AS Name FROM Employee ORDER BY LastName", SqlConn); SqlConn.Open(); ddl.DataSource = SqlCmd.ExecuteReader(CommandBehavior.CloseConnection); ddl.DataTextField = "Name"; ddl.DataValueField = "UID"; ddl.DataBind(); }