## PHPMyAdmin blank whitescreen (414 Request-URI Too Long)

Ran across an interesting issue where PhpMyAdmin on a newly installed CentOS server was not rendering in a browser. Or more accurately, it was rendering but the CSS kicked in and caused the browser to display a blank page rather than the desired login screen. (Doing a View Source on the page showed that the login form was in fact there, but hidden by CSS.)

After checking the obvious things: PHP running (with error reporting on), file permissions, Apache working, VirtualHost definition correct, I was stuck. There were no indications of a problem, and PHP reported nothing. (Because, as we will see, there were no errors to be displayed…or was there?)

Finally, I turned on Firebug and refreshed the page. Voilà! There were actually two issues, but they were hidden within additional calls in the backend:

Wow, those two long URL strings! One URL was:

A quick search uncovered a possible fix. The default Apache limit of the request line needed to be made longer to accomodate PhpMyAdmin. Doing this was simple. I added the directive to ‘/etc/httpd/conf/httpd.conf’ like so:

LimitRequestLine 800

I tried a few different lengths and found that 700 was too short, but 800 worked fine. Also, though I simply added this to the conf file, according to the docs you can add this within the VirtualHost rather than making it blanket covering the entire server.

Hope this helps others.

## Ubuntu 16.04 and PHP 7 not rendering

After reloading my work laptop with Ubuntu 16.04 LTS (I prefer to do a reload versus an upgrade, for each LTS version) I was very excited to install PHP 7, and installed using the standard Ubuntu repositories using typical commands:

$sudo apt-get install apache2$ sudo apt-get install php7.0

However, after doing the installs I discovered PHP scripts would not render in a browser. After a small amount of digging I realized that doing the base installs did not include one important piece. The package ‘libapache2-mod-php7.0’ was not automatically installed as expected, as it did in the past. (I don’t remember needing to install it separately in the past.) Hopefully the package maintainers fix this at some point. Your mileage may vary.

## Finding Duplicates using SQL

While migrating old data to a new database schema I was unable to activate a PRIMARY KEY on the legacy_customer_id field because there were duplicates. It turned out that the old application did not clean the data really well, and it allowed duplicates to be created where one of the customer_ids had a space character making it unique.

I used the following query to test for others:

SELECT customer_id, COUNT(customer_id) FROM customers GROUP BY customer_id HAVING (COUNT(customer_id) > 1);

This allowed me to find all customer_ids that had duplicates and clean things up.