Before beginning, make a backup copy of your database. Then, login to your database using phpMyAdmin (or whatever), and navigate to the “active_plugins” column of the “wp_options” table using the following SQL query (edit the default WordPress table prefix “wp_” if needed):
SELECT * FROM wp_options WHERE option_name = 'active_plugins';
Once the active_plugins column appears, click to edit it. You will see something similar to the following, depending on the number and type of plugins you have installed:
a:31:{i:0;s:13:"AddMySite.php";i:1;s:19:"akismet/akismet.php";i:2;s:23:"all_in_one_seo_pack.php";i:3;s:16:"authenticate.php";i:4;s:28:"breadcrumb-navigation-xt.php";i:5;s:18:"codeautoescape.php";i:6;s:37:"contact-coldform/contact_coldform.php";i:7;s:32:"custom-query-string-reloaded.php";i:8;s:30:"customizable-post-listings.php";i:9;s:33:"dd-sitemap-gen/dd-sitemap-gen.php";i:10;s:20:"download-counter.php";i:11;s:13:"feedcount.php";i:12;s:13:"full_feed.php";i:13;s:15:"get-weather.php";i:14;s:36:"google-sitemap-generator/sitemap.php";i:15;s:13:"gravatars.php";i:16;s:19:"kill-admin-nags.php";i:17;s:18:"landingsites13.php";i:18;s:30:"nofollow-free/nofollowfree.php";i:19;s:17:"ol_feedburner.php";i:20;s:16:"plugins-used.php";i:21;s:22:"popularity-contest.php";i:22;s:39:"search-everything/search_everything.php";i:23;s:27:"simple-tags/simple-tags.php";i:24;s:26:"simple_recent_comments.php";i:25;s:18:"simple_twitter.php";i:26;s:25:"subscribe-to-comments.php";i:27;s:24:"the-excerpt-reloaded.php";i:28;s:18:"theme-switcher.php";i:29;s:9:"top10.php";i:30;s:16:"wp-db-backup.php";}That entire array of code represents every active plugin on your site. Thus, to quickly disable all plugins without using the WP Admin area, highlight the entire block of code, cut it out, and paste it into a safe, offline text file. After removing the code, click the button to save your changes and that’s it. All WordPress plugins are now deactivated (yet still installed, and with all plugin options intact). This obviously is a huge time-saver that really comes in handy during those mission-critical, time-sensitive situations where every second counts. Once you are ready to re-activate your entire set of plugins, simply cut/copy & paste the preserved code back into the “active_plugins” field. Click save and done. Again, don’t forget to backup your database before editing it 😉
Alternately, here is a one-second query to disable all plugins. this method works only for WordPress versions 2.9 and later:
UPDATE wp_options SET option_value = 'a:0:{}' WHERE option_name = 'active_plugins';Upon execution, this query will clear the active_plugins field of all active plugins (duh), effectively disabling (without uninstalling or modifying) the entire set. This method is great if you plan on re-enabling each plugin individually, say, after resolving some heinous server error. Whereas the previous technique makes it easy to re-enable all plugins en masse, this query is perfect for simply “nuking” all active plugins with no remorse.
Source: http://perishablepress.com/quickly-disable-or-enable-all-wordpress-plugins-via-the-database/