i tried but it is not working in combo box data is not retrieved from the database

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My code as follows

In pageload i written the below code as follows

C#

SqlConnection conn = new SqlConnection(@"Data Source=DOCTOR\SQLEXPRESS;Initial Catalog=Testing;User ID=sa;Password=a");

conn.Open();
SqlCommand sc = new SqlCommand("select Designation from Designations where active <> 'd'", conn);
 SqlDataReader reader;
 reader = sc.ExecuteReader();
 DataTable dt = new DataTable();
 dt.Columns.Add("Designation", typeof(string));
 dt.Load(reader);
 dt.Load(reader);
 ComboBox1.DataTextField = "Designation";
 ComboBox1.DataValueField = "Designation";
 ComboBox1.DataSource = dt;
 ComboBox1.DataBind();
 conn.Close();

In run mode as follows
Designation Combobox

But in combobox designation is not displayed. I tried several time but in combobox designation is not shown.

Please help me what is the problem in my above code.

Posted 13-Aug-15 16:30pm

narasiman1

Updated 13-Aug-15 17:34pm

Wendelius

v3

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DamithSL 14-Aug-15 0:13am

any exceptions? debug and check reader has records or not

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Wendelius · Answer 1 · 2015-08-13T17:32:00

There are quite a few possible problems, like:

The condition of the query causes no rows to be returned
The table is empty
The ComboBox1 isn't actually the correct object and so on

Also you seem to call the data table's Load method twice. Never tested, what happens if the load is called the second time with the same reader....

Anyhow You should us the debugger to see what actually happens. Place a breakpoint on the first line and go through the code step-by-step. Using the debugger, investigate what is the content of different variables, does the query return rows and so on.

But actually before doing even that, I would suggest the following modifications:

Instead of using the reader and loading the data table, I'd use SqlDataAdapter, define the SelectCommand[^] and use the SqlDataAdapter.Fill[^] to populate the data table.
I suggest renaming the objects to something meaningful instead of the default names like ComboBox1. This helps to understand the code and also to spot errors.

DamithSL · Answer 2 · 2015-08-13T18:22:00

Read Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^] and try to debug your application and check the values you get at runtime and also which objects not behave as you expected.
you can fill Datatable using SqlDataAdapter[^] and set the datatable as DataSource, sample code:

C#

using(SqlConnection con = new SqlConnection(ConnectionString))
using(SqlCommand cmd = new SqlCommand("select Designation from Designations where active <> 'd'", con))
using(SqlDataAdapter da = new SqlDataAdapter(cmd))
{
     DataTable dt=new DataTable();
     da.Fill(dt);
     ComboBox1.DataTextField = "Designation";
     ComboBox1.DataValueField = "Designation";
     ComboBox1.DataSource = dt;
     ComboBox1.DataBind();
}

run the sql statement in sql management studio and make sure you have data for the sql statement. debug and check above code and check the datatable rows. update the question with exception details if any.

i tried but it is not working in combo box data is not retrieved from the database

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