Question

Hi I have been learning php from this book PHP Solutions Dynamic Web Design Made Easy and gotten to the part where I have to work with mysqli api for databases.After writing a connection function and running the script I get this error:

This is my code:

function dbConnect($usertype , $connectionType = 'mysqli'){
    $host = 'localhost';
    $db = 'phpsols';
    if($usertype == 'read'){
        $user = 'psread';
        $pwd = 'Aleczandru1989';
    }elseif($usertype == 'write'){
        $user = 'aleczandru';
        $pwd = 'Aleczandru1989';
    }else{
        exit('Unrecognized type');
    }

    if($connectionType == 'mysqli'){
        return new mysqli($host , $user , $pwd , $db) or die ('Cannot open database');
    }else{
        try{
            return new PDO("mysql:host=$host;dbname=$db", $user, $pwd); 
        }  catch (PDOException $e){
            echo 'Cannot connect to database';
            exit;
        }
    }
}

$conn = dbConnect('read');
$sql = 'SELECT * FROM images';
$result = $conn->query($sql) or die(mysqli_error()); //Line 5
$numRows = $result->num_rows;

Line 5 in this case refers to $result = $conn->query($sql) or die(mysqli_error());.
What Am I doing wrong here?

Answer 1

The $conn object you are attempting to create with dbConnect(‘read’); fails. If you would do a var_dump($conn); it probably shows it is not what you aspect it to be. The error is actually describing what is wrong. You try to access the query function with ‘->query(..’ on $conn. But $conn has to be an object reference that actually has the query function. The points where this object will be created are:

return new mysqli($host , $user , $pwd , $db)

and

return new PDO("mysql:host=$host;dbname=$db", $user, $pwd); 

Since you are showing a different error then

or die ('Cannot open database');

My guess it is actually gong wrong at

return new PDO("mysql:host=$host;dbname=$db", $user, $pwd);

And you will catch the exception. But the echo statement is not visible anymore due to the fatal error. You will have to do some debugging there!

I have no experience with PDO, but construction of the object seems ok. (but can this help you out: https://www.php.net/manual/en/class.pdo.php#84751) If the construction is ok, than check if your database engine is actually running 🙂 ?