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The site is currently not available due to technical problems. Please try again later. Thank you for your understanding.

If you are the maintainer of this site, please check your database settings in the settings.php file and ensure that your hosting provider’s database server is running. For more help, see the handbook, or contact your hosting provider.

There are two things you need to check.

1. Is mysqli is installed or not?

2. Is server able to connect database?

Is mysqli installed or not:

Check info.php file is mysqli is listed in this page, if not then your server will support only mysql not mysqli. If your host doesn’t have mysqli installed, you can it change to use mysql. (MySQLi stands for MySQL Improved.)

Open settings.php change $db_url from mysqli to mysql (settings usually in /sites/default-folder in your drupal installation).

BEFORE:
$db_url = ‘mysqli://user:password@hostname/table’;

AFTER
$db_url = ‘mysql://user:password@hostname/table’;
This means that you can either install MySQLi with your PHP install OR you can simply make the changes to your settings.php file as detailed above.

 Is server able to connect database?

Check whether you have passed right username, password and database name and also check whether you have given full permission to access the database from the server.

Hope this will be useful for those having similar problems.

Test your Drupal Skills

Drupal Architecture Diagram

This is really useful those who wants to understand the schema and its flow. For better view, right click on the image and view the image the separately…
schemagraph-2007-10-18

Disable drupal modules using MySQL query

I am doing a project in drupal.  After enabling a module, my site is not loading and i can’t able to disable that module.  so i start searching Google and found this easy solution. May be it will be helpful for others who have similar problems.

Connect to your mysql shell or phpmyadmin and then use following query to disable a module:

UPDATE system SET status=0 WHERE name='module name';

Remember to change module name to the name of the module you want  to disable. 
This action will disable that module so that administrators can access to the administration panel again.

To list all drupal modules:

SELECT * FROM system WHERE type='module';