选择查询代码以返回listitem值

Question

我正在尝试输入listitem值结果的选择查询代码，但是我收到了这个错误：

  

无效的列名称＆＃39; adam＆＃39;。

我不知道代码有什么问题。

  

https://i.stack.imgur.com/kpUDu.jpg

这是代码：

private void listBox1_MouseDoubleClick(object sender, MouseEventArgs e)
    {
        label11.Text = "";
        t1.Text = "";
        t2.Text = "";
        t3.Text = "";
        t4.Text = "";
        t5.Text = "";
        t6.Text = "";
        t7.Text = "";
        t8.Text = "";
        cb2.Text = "";
        pb1.Image = null;
        con.Open();
        String sqlselectquery = "select * from employee where emp_id=" + listBox1.SelectedValue;
        SqlCommand cmd = new SqlCommand(sqlselectquery, con);
       SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            t1.Text = (dr["emp_id"].ToString());
            t2.Text = (dr["emp_name"].ToString());
            t3.Text = (dr["emp_birth"].ToString());
            t4.Text = (dr["emp_id_code"].ToString());
            t5.Text = (dr["emp_add"].ToString());
            t6.Text = (dr["education"].ToString());
            t7.Text = (dr["hiredate"].ToString());
            t8.Text = (dr["salary"].ToString());
            cb1.SelectedValue = (dr["job_id"].ToString());
            cb2.Text = (dr["emp_rel"].ToString());
            byte[] img = (byte[])(dr["emp_pic"]);
            MemoryStream ms = new MemoryStream(img);
            pb1.Image = Image.FromStream(ms);
        }
        con.Close();
    }