Fatal error: Undefined class constant ‘ATTR_DEFAULT_FETCH_MODE’

This is one of the common error messages that seems to appear after installing PHP – in particular under Ubuntu or Debian (where I experienced it). The reason for this is that the PDO version you’ve just installed is too old for the constant to exist, usually because you where naive enough to install the extension from PECL instead of using the default supplied by ubuntu. If you did the same as me:

apt-get install 
pecl install pdo
pecl install pdo_mysql

/etc/init.d/apache2 restart

And everything seems to work, except for that missing constant. What the fsck?!

The reason is that the PECL version of PDO is no longer maintained (I’d suggest to automagically push the newest version to PECL too, just so pecl install and pecl upgrade works as expected). The fact is that when you did pecl install pdo, you destroyed the more recent version provided by the default php5-common package (under Ubuntu, at least).

To solve the problem (and if you also did pecl install pdo_mysql, you’ll have to replace that one too…)

apt-get install --reinstall php5-common php5-mysql php5-mysqli

Restart. Relive. Re.. eh .. yeah. Rerere.

If you’re building from source, you’ll need to add:

--enable-pdo --with-pdo-mysql --with-pdo-pgsql (and any other driver you need)


Hi there Mr. PDO!

We’ve come to know each other, and yes, while you have your troubles (.. which I don’t, of course), I’ve accepted your short comings. Today you threw another one of your fits, but I’ll be sure to document it for the world to see.

$statement = $pdo->prepare("
        :offset, :hits

Yep. This will of course fail if you’re binding strings. ’10’, ’10’ is not very helpful now, is it. Good point. So let’s tell PDO that we’re really binding ints:

$statement->bindValue(':offset', $offset, PDO::PARAM_INT);
$statement->bindValue(':hits', $hits, PDO::PARAM_INT);

But wait. You’re still complaining?! I told you they were ints?! What’s the problem now?!?!

Well. Mr. PDO requires you to also convert the values for him. So first you have to convert the values of a loosely typed language to a strong type, then you have to tell the library that yes, this is in fact another type than what the library obviously assumes that it is. This works:

$statement->bindValue(':offset', (int) $offset, PDO::PARAM_INT);
$statement->bindValue(':hits', (int) $hits, PDO::PARAM_INT);

Which means the following:

If the type of your variable internally is a string, it’ll be escaped as a string, even if you tell PDO that it should be handled as an INT in your database layer.

If the type of your variable is an int, it’ll be handled as a string, unless you tell PDO it is an int.

Something is backwards here.

Undefined symbol: php_pdo_declare_long_constant

After installing a new PDO module (PDO_PgSQL) into our compiled-from-the-ground-up version of PHP 5.2.8 (.. since RHEL4 doesn’t really stay updated, but we do), i ran head first into the following issue:

/usr/sbin/httpd: symbol lookup error: /usr/local/lib/php/extensions/no-debug-non-zts-20060613/pdo_pgsql.so: undefined symbol: php_pdo_declare_long_constant

Panic. Then tried updating pdo_mysql which actually still worked, which just led it to have the exact same problem. Luckily a bit of searching at Google pointed me to PDO_MYSQL causing Apache segfault over at the PECL bug tracker. The last comment provided the solution to the problem: a quick rebuild of PHP with –disable-pdo and then enabling pdo from PECL instead (so that PDO and the PDO plugins API actually match, instead of trying to load the wrong version into the process) solved the issue.

Be sure to build PDO from the SAME VERSION as your client libraries. Disable it in the PHP build itself if you need to build it from PECL.