PHP multi-dimensional arrays

[James_43]

Hi there,

I am trying to populate a page with multiple rows from a mySQL database.

To grab the data, I am using:

for ($i=1; $i < 5; $i++) {

        $query = 'SELECT * FROM table WHERE column = ?';
        $statement = $mySQL_con->prepare($query);

        try {
            $statement->execute(array($i));
        }

        catch (PDOException $error) {
            echo 'Sorry, we failed to load this page: ' . $error->getMessage();
        }

        $row = $statement->fetch();
        $results[] = $row;
}

That creates a mutil-dimensional array. However, when I try to access that data things go a bit weird.

For example,print_r($results[2][name]); should output the name from the third row I grabbed using the mySQL query (third because PRIMARY KEY > 0). Instead, I get the error message: "Use of undefined constant blog_id - assumed 'blog_id'"

The strange thing is that directly underneath that error message, I get the name value from the array I wanted.

[Gideon_1]

Have you executed this query in the mysql client or phpmyadmin

[James_43]

I have created the connection through PHP:

//mySQL Credentials
$mySQL_username = 'username';
$mySQL_password = 'password';
$mySQL_host = 'localhost';
$mySQL_database = 'database';

//Attempt mySQL Connection
    try {
        $mySQL_con = new PDO('mysql:host='.$mySQL_host.'; dbname='.$mySQL_database.'', $mySQL_username, $mySQL_password);
        }

    catch (PDOException $error)
        {
        echo "Unable to connect: " . $error->getMessage();
        }

The query itself works, since the data from the array is complete when displayed with the print_r function.

[jkon]

Hello James,
PHP associative arrays (that are the one returned by PDO fetch PDO::FETCH_ASSOC @see http://php.net/manual/en/pdostatement.fetch.php ) need quotes if the key is string . e.g. $results[2]["blog_id"] . If you don't have quotes PHP will search for the constant with name blog_id , that this is your case here (you didn't define @see http://php.net/manual/en/function.define.php so you have that message). That doesn't happen only for arrays resulted by PDO fetch but for any PHP array.

Except for that I am not quite sure I understand what you are trying to do , e.g. why you have a query inside a for loop. Maybe there is a reason for that but I guess that you want actually to do something different from what you wrote. If you want you can explain further what you are trying to do to fix that also.

[James_43]

Hey Jkon,

Thanks for that - that was my mistake, I forgot to put the quotations round the string. Sorted now.

You're right about the for loop. At the time, I was thinking that was the only way to grab multiple rows of data from mySQL, because when I tried with a query that returned multiple rows for some reason the array was only storing the information from the first row.

I realise now it was because I needed to push the data from each row into the array. So I can ditch the for loop and instead use $results[] = $row;

Thanks for your advice!