Get value with reader from another form c#

Question

Need string to label

 

InitializeComponent();
korisnickoImeLabel.Text = getKorisnickoIme();

 

What I wrong?

Query is ok

 

private String getKorisnickoIme()
        {
            SqlConnection myConnection = new SqlConnection(cs);
            String value = "SELECT ime_prezime FROM osobe_korisnici WHERE id='" + korisnikId + "'";
            SqlCommand cmd = new SqlCommand(value, myConnection);
            myConnection.Open();
            SqlDataReader rdr = cmd.ExecuteReader();
            return value;

        }

 Result in label is

 SELECT ime_prezime FROM osobe_korisnici WHERE id='10'

 

 

id is 10, but I need to write in label name and surname for user (ime_prezime)