如何将信息从数据库加载到 Asp.Net 中的标签？

Question

I would like to load a data from a specific column in the database when a user clicks on a link button from the previous page.

I am using the SqlDataReader to do this, but I get the error:

Index was outside the bounds of the array.

Here is my code:

private void loadDetails()
{
    if (con.State == ConnectionState.Closed)
        con.Open();
    SqlCommand cmd = new SqlCommand("select expectation from Tours where tourName ='" + tournameLb.Text + "'", con);
    cmd.CommandType = CommandType.Text;
    cmd.Parameters.AddWithValue("@expectation", lb5.Text);

    SqlDataReader dr = cmd.ExecuteReader();

    while (dr.Read())
    {
        lb5.Text = dr[4].ToString(); //I get error here 
    }
    dr.Close();
    con.Close();
}

Where

tournameLb.Text = Session["tourName"].ToString();

Answer 1

You're using a parameter for the value, which is the good way, but you need to use a parameterized query with it:

SqlCommand cmd = new SqlCommand("select expectation from Tours where tourName = @expectation", con);

Also your query will only return one columns, but you're trying to get the value of the fifth column which doesn't exist:

lb5.Text = dr[0].ToString();

Alternatively, you can use the name of the column instead of the index:

lb5.Text = dr["expectation"].ToString();