Check username(u) and password(p) to display all outcomes -empty fields,wrong u,wrong p, wrong u and p,correct u and p depending on the input?

if(username or password field is empty) { display msg; } else if(username and password field is correct) { display msg } else if (username field is wrong) { display msg; } else if (password field is wrong) { display msg; } else (username and password field is wrong) { display msg; }