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Displaying posts with tag: pdo (reset)
Apache on Fedora 30

There was an option during the Fedora 30 Workstation installation to add the Apache Web Server, but you need to set it to start automatically. Unfortunately, there was no option to install PHP, which I thought odd because of how many web developers learn the trade first on PHP with a LAMP (Linux, Apache, MySQL, Perl/PHP/Python) stack. You see how to fix that shortcoming in this post and how to install and test PHP, mysqli, and pdo to support MySQL 8.

Before you do that make sure you install MySQL 8. You can find my prior blog post on that here.

You set Apache to start automatically, on the next boot of the operating system, with the following command:

chkconfig httpd on

It creates a symbolic link:

Created symlink /etc/systemd/system/multi-user.target.wants/httpd.service → …
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MySQL and PHP Basics Part I

I have had some requests to write some blogs on the basics of using PHP and MySQL together.  This will not be a series for the experienced as it will start at a level where I will go into a lot of details but expect very few prerequisites from the reader.  If this is not you, please move on. If it is you and you read something you do not understand, please contact me to show me where I assumed too much.

PHP and MySQL are both in their mid twenties and both vital in the worlds of developers.  With the big improvements in PHP 7 and MySQL 8, I have found a lot of developers flocking to both but stymied by the examples they see as their are many details not explained. So let's get to the explaining!
1. Use the latest software
If you are not using PHP 7.2 or 7.3 (or maybe 7.1) then you are missing out in features and performance.  The PHP 5.x series is deprecated, no longer support, and …

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Connecting PHP to MySQL on Bluemix

Most of the PHP I write runs on Bluemix - it's IBM self-service cloud, and since I work there, they pay for my accounts :) There are a bunch of databases you can use there, mostly open source offerings, and of course with PHP I like to use MySQL. Someone asked me for my connection code since it's a bit tricky to grab the credentials that you need, so here it is. Bluemix Environment Variables

In Bluemix, you can simply create a MySQL database (look for "compose-for-mysql" in the catalog), create a set of credentials, and then bind it to your app. I should blog a few more of my PHP-on-Bluemix tricks but you can run a selection of PHP versions and it's also possible to add extensions that you need, I have found it does have what I need once I figure out how to configure it!

Once the database is bound to the application, then your PHP code running on Bluemix will have an environment variable called VCAP_SERVICES. The …

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Types in PHP and MySQL

Since PHP 7.0 has been released there's more attention on scalar types. Keeping types for data from within your application is relatively simple. But when talking to external systems, like a database things aren't always as one eventually might initially expect.

For MySQL the type we see -- in the first approximation -- is defined by the network protocol. The MySQL network protocol by default converts all data into strings. So if we fetch an integer from the database and use PHP 7's typing feature we get an error:

<?php
declare(strict_types=1);

function getInteger() : int {
  $mysqli = new mysqli(...);
  return $mysqli->query("SELECT 1")->fetch_row()[0];
}

var_dump(getInteger());
?>

Fatal error: Uncaught TypeError: Return value of getInteger() must be of the type integer, string returned in t.php:6

Of course the solution is easy: Either we cast ourselves or we disable the strict mode and PHP will …

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Handling SQL Errors in PDO

I love PHP's PDO (PHP Data Objects) extension; it gives a consistent, object-oriented interface to handling all kinds of relational database backends. One thing that annoys me is that the MySQL driver for PDO defaults to a silent error mode which can make SQL errors tricky to spot!

To give you an example, consider the query below (the correct tablename is country, so this SQL will fail):

$db = new PDO('mysql:host=localhost;dbname=sakila', 'user', 'pass');

$sql = 'select * from countrt';
$stmt = $db->query($sql);

while(($row = $stmt->fetch()) != false) {
    echo $row['country'] . "\n";
}

The script will output an error because $stmt is not an object.

You have a few options here - you can check that you got an object back before you try to do anything with it, for example. Alternatively you can prepare() and then …

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Handling SQL Errors in PDO

I love PHP's PDO (PHP Data Objects) extension; it gives a consistent, object-oriented interface to handling all kinds of relational database backends. One thing that annoys me is that the MySQL driver for PDO defaults to a silent error mode which can make SQL errors tricky to spot!

To give you an example, consider the query below (the correct tablename is country, so this SQL will fail):

$db = new PDO('mysql:host=localhost;dbname=sakila', 'user', 'pass');

$sql = 'select * from countrt';
$stmt = $db->query($sql);

while(($row = $stmt->fetch()) != false) {
    echo $row['country'] . "\n";
}

The script will output an error because $stmt is not an object.

You have a few options here - you can check that you got an object back before you try to do anything with it, for example. Alternatively you can prepare() and then …

[Read more]
Scalar type hints in PHP trunk

So in my blog series I try to cover all additions to PHP trunk so I have to mention scalar type hints.

<?php
function print_float(float $f) {
    echo $f."\n";
}

for ($i = 1; $i < 5; $i++) {
    print_float( $i / 3 );
}
?>
        

0.33333333333333
0.66666666666667

Catchable fatal error: Argument 1 passed to print_float() must be of the type double, integer given, called in typehints.php on line 7 and defined in typehints.php on line 2

Is expected behavior in PHP's trunk. If you want such a thing to work please use the numeric type hint.

In case that wasn't enought fun: There's more!

<?php
function handle_result(int $i) {
    echo $i."\n";
}

$pdo = new PDO("mysql:host=localhost;dbname=test", "user", "pass"); …
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Jumpstarting PDO

Lukas is making another attempt at jumpstarting PDO development.  I welcome this effort, and will do what I can to help fill in details and make suggestions.  Unfortunately, I'm just way too busy with work to be able to commit to more than that.

I also wanted to share some of my thoughts on why PDO has been in a holding pattern for a while, so that more people are aware of it and can work to avoid repeating the same mistakes.

The first thing to note is that the guts of PDO were hard to develop.  The PHP script facing API sounds simple enough, but the underlying libraries for each different databases work in different ways, and it was and is a challenge to build PDO in such a way that it can work in the most efficient way.

The second thing, which is really a follow-on from the first, is that the database libraries are complex and nuanced.  …

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Developing MySQL Database Applications With PHP

A four part tutorial that explains the PHP / MySQL extensions - mysql, mysqli, and pdo_mysql - with simple examples is now accessible from Sun Developer Network. While most of the information presented in the tutorial is available elsewhere in bits and pieces, the real value-add is in the introduction of the MySQL native driver for PHP, mysqlnd.

Here is a brief description of all four parts in the series. Check them out, and as always feel free to send the corrections, comments, suggestions, etc., to my Sun mail ID: Giri.Mandalika@Sun.COM

[Read more]
Developing MySQL Database Applications With PHP

A four part tutorial that explains the PHP / MySQL extensions - mysql, mysqli, and pdo_mysql - with simple examples is now accessible from Sun Developer Network. While most of the information presented in the tutorial is available elsewhere in bits and pieces, the real value-add is in the introduction of the MySQL native driver for PHP, mysqlnd.

Here is a brief description of all four parts in the series. Check them out, and as always feel free to send the corrections, comments, suggestions, etc., to my Sun mail ID: Giri.Mandalika@Sun.COM

[Read more]
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