为什么我在文本框中得到无效的输出？

Question

The output of textbox 1 2 and 4 are coming as a single character followed with spaces.

Example: like the value in the DB is 40 then in textbox its appearing as 4.

The datatype is Nchar(10) and of one column is int. In both the case the invalid output occurs.

namespace WebApplication2
{
    public partial class WebForm2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {    
        }      

        public void SomeMethod()
        {
            using (var conn = new SqlConnection(
                                 "Data Source=soniya-9393b956;Initial Catalog=tabby;Integrated Security=True;Pooling=False"))
            {
                conn.Open();

                using (var cmd = new SqlCommand("select * from students where ID=" + textBox1.Text, conn))
                using (var rdr = cmd.ExecuteReader())
                   while (rdr.Read())
                   {
                       TextBox1.Text = rdr["id"].ToString();
                       TextBox2.Text = rdr["name"].ToString();
                       TextBox3.Text = rdr["class"].ToString().Trim();
                       TextBox4.Text = rdr["roll"].ToString();
                       //  builder.Append(rdr[0]).Append(Environment.NewLine);
                   }        
              }        
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            SomeMethod();
        }
     }
 }

Answer 1

Adi, after looking at the source you sent and the database schema, it looks like it should all work, I'm wondering if your connection string is incorrect given the schema you sent in our SO chat session. When I changed the connection string to my hostname and database name, it worked as expected:

"Data Source= YourHostName ;Initial Catalog= YourDatabaseName ;Integrated Security=True;Pooling=False"

You list tabby in your connection string, but in the schema you cut and paste in chat it stated Use [Demo] as the database, which leads me to believe it may be a connection string issue.

Answer 2

Do your charsets match? The unicode coming from the database stored as NCHAR might get mangled if the C# code is expecting something else.

Answer 3

Could be that you just forgot to put your code in the proper brackets for SqlCommand and Reader:

using (var cmd = new SqlCommand("select * ... " + textBox1.Text, conn))
{
    using (var rdr = cmd.ExecuteReader())
    {
        while (rdr.Read())
        {
         ...
        }
    }
}