Check if the name is already registered in the Database

Question

This is a Mangáka registration screen, so if I type a name it is added without problems, however I want to check if there is already any record with that name.

Table:

create table tblMangaka(
                        idMangaka int(20) auto_increment primary key,
                        Mangaka varchar(500)
                       );

Code C#, would be at the beginning would do the checking, if text txtNome is already inserted in table tblMangaka.

strMysql = "insert into dbMangas.tblMangaka (Mangaka)values(@Mangaka);";

MySqlCommand comando = new MySqlCommand(strMysql, con);
comando.Parameters.AddWithValue("@Mangaka", txtNome.Text);

try
{
    con.Open();
    comando.ExecuteNonQuery();
}
catch (Exception erro)
{
    MessageBox.Show("Ocorreu um erro:\n" + erro);
}
finally
{
    MessageBox.Show("Mangáka Cadastrado!", "Mangáka", MessageBoxButtons.OK);
    txtNome.Clear();
    txtNome.Focus();
    con.Close();

    inserirCmbMangaka();
}