求一赋值语句，网label里面赋值

Question

 protected void TextBox1_TextChanged(object sender, EventArgs e)
    {
        SqlConnection libCon = new SqlConnection("Data Source=.\\sqlexpress;Initial Catalog=library;Integrated Security=True");
        libCon.Open();
        string BorSQL;
        BorSQL = "select rName from borrow where bookid = '"+TextBox1.Text+"';";
        SqlCommand StuIns = new SqlCommand(BorSQL, libCon);
        SqlDataReader libDa = StuIns.ExecuteReader();
        libDa.Read();
        Response.Write(label1.Text =
        libCon.Close();
       
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我想从通过TextBox1.Text输入，从borrow表里查询到rName 并输入到label1里面

Answer 1

   
    string sql = " select rName from borrow where bookid =@bookid";
    using (SqlConnection conn = new SqlConnection("Data Source=.\\sqlexpress;Initial Catalog=library;Integrated Security=True"))
    {
        SqlCommand cmd = new SqlCommand(sql, conn);
        cmd.Parameters.Add("@bookid", SqlDbType.VarChar);
        cmd.Parameters["@name"].Value = TextBox1.Text;
        try
        {
            conn.Open();
            label1.Text= cmd.ExecuteScalar()==null?"":cmd.ExecuteScalar().ToString();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    

Answer 2

 cmd.Parameters.Add("@bookid", SqlDbType.VarChar);
        cmd.Parameters["@bookid"].Value = TextBox1.Text; //囧  更正

Answer 3

protected void TextBox1_TextChanged(object sender, EventArgs e)
  {
  using(SqlConnection libCon = new SqlConnection("Data Source=.\\sqlexpress;Initial Catalog=library;Integrated Security=True"))
  libCon.Open();
  string BorSQL;
  BorSQL = "select rName from borrow where bookid = '"+TextBox1.Text+"'";
  using(SqlCommand StuIns = new SqlCommand(BorSQL, libCon))
  {
       using(SqlDataReader libDa = StuIns.ExecuteReader())
       {
          while(libDa.Read())
         {
            label1.Text = libDa["rName"].ToString();
          }
        }
   }
}