无法使用数据阅读器显示列条目

Question

SqlConnection con = new SqlConnection("My path");
SqlCommand cmd;
SqlDataReader dr;

Label1.Text = Session["name"].ToString();

con.Open();
cmd = new SqlCommand("Select '"+Session["name"]+"' from table1",con);
dr = cmd.ExecuteReader();

while(dr.read()){
   Dropdownlist1.Items.Add();   ------->Stuck here
}

I am selecting a column from a table which will have 3 or more entries. And I want to put them in dropdownlist. I tried different approaches but nothing is giving me output I require. It shows error or display first entry only.

Please feel free to edit my code and provide a suitable idea.

THANKS

This is my table:

SKY  |  SEA  | LAND
-----------------------
EAGLE| SHARK | LION
CROW | FISH  | TIGER
DUCK | WHALE | DEER   

Where Session["name"] can be SKY/SEA/LAND and depending on that I want my drop down to show the entries below it IF SKY is Session["name"] then dropdwonlist should display EAGLE CROW DUCK

Answer 1

Have you tried?

 while (dr.read()){
      Dropdownlist1.Items.Add(dr["Name"].ToString());
 }

If you want to go get only once and without also having to specify the column name then you could use GetString(0) like:

 while (dr.read()){
      Dropdownlist1.Items.Add(dr.GetString(0));
      break;
 }

Answer 2

Base on your question you are passing Session["name"] which is your table Column Name to your select query.

There is also need to change on your code:

Lets say your Session["name"] value is SKY

"Select '"+Session["name"]+"' from tableA" --session["name"] is treated here as a string

this will be rendered as Select 'Session[Name]' from TableA which is incorrect. so the result will be :

Session[Name]
Session[Name]
Session[Name]

Remove the single quote on the query and let's say : Session["name"] value is SKY

cmd = new SqlCommand("Select "+Session["name"].ToString()+" from table1",con);

the query will be -> Select SKY from table1

and the select result

EAGLE 
CROW 
DUCK

If so try this :

SqlConnection con = new SqlConnection("My path");
SqlCommand cmd;
SqlDataReader dr;

Label1.Text = Session["name"].ToString();

con.Open();
cmd = new SqlCommand("Select "+Session["name"].ToString()+" from table1",con);
dr = cmd.ExecuteReader();

       while (dr.Read())
        {
                   // get the results of each column
                   Dropdownlist1.Items.Add(dr[0].ToString()); //this will get your first column even your Session["name"] will contain any column values

        }

Check also this tutorial: Lesson 04: Reading Data with the SqlDataReader

Best Regards

Answer 3

you should use like below

while (dr.read()){
  ListItem l = new ListItem(dr["name"].ToString(), "value", true);
  Dropdownlist.Items.Add(l);
}