mysqli_query gives empty value - php

Question

Im creating a login system for my website.
I got the problem that my mysqli_query is empty:
The code: $r = mysqli_query($dbc, $q); returns empty.
I think the problem is in the sql language that i pass it:
$q = "SELECT userid, fname, lname FROM User WHERE email='$e' AND pass=SHA1('$p')";
If i execute the sql above with the data that im actually is fetching from the form then i will get the result Im looking for. So i think its the php and sql combined that got an error.
if(empty($errors)){
$q = "SELECT userid, fname, lname FROM User WHERE email='$e' AND pass=SHA1('$p')";
$r = mysqli_query($dbc, $q);
//Check for right data
$errors[] = $e;
$errors[] = $p;
//Check if connection is up
if($dbc != null){
$errors[] = "Connection up";
}
//Check query
if(is_null($r)){
$errors[] = "Query is null";
}
//Check query for being empty
if(empty($r)){
$errors[] = "Its empty";
}
if( mysqli_num_rows($r) == 1){
$row = mysqli_fetch_array($r, MYSQLI_ASSOC);
return array(true, $row);
}else{
$errors[] = "Email address and password not found.";
}
return array(false, $errors);
}

Answer 1

You can try this
if(empty($errors)){
$p = sha1($p);
$q = "SELECT userid, fname, lname FROM User WHERE email = '$e' AND pass = '$p'";
$r = mysqli_query($dbc, $q);
if(!$r){
die(mysqli_error($dbc));
}
//Check for right data
$errors[] = $e;
$errors[] = $p;
//Check if connection is up
if($dbc != null){
$errors[] = "Connection up";
}
//Check query
if(is_null($r)){
$errors[] = "Query is null";
}
//Check query for being empty
if(empty($r)){
$errors[] = "Its empty";
}
if( mysqli_num_rows($r) > 0){
$row = mysqli_fetch_assoc($r);
return array(true, $row['userid'], $row['fname'], $row['lname']);
}else{
$errors[] = "Email address and password not found.";
}
return array_merge(array(true), $errors);
}