Magento exception.log PDOException cause and fix?

Magento exception.log PDOException cause and fix?

References

Reference NO 1

http://stackoverflow.com/questions/15200456/magento-exception-log-pdoexception-cause-and-fix

Reference NO 2

http://www.albertomariarossi.it/howto-solve-url-rewrite-indexing-errors-in-magento/

Reference NO 3

http://www.magentocommerce.com/boards/viewthread/246805/

Reference NO 4

http://www.brownwebdesign.com/blog/2011/12/debugging-magento-duplicate-entry-database-error-2/

Reference NO 5

https://drupal.org/node/1163740

Reference NO 6

https://github.com/Vinai/groupscatalog2/issues/24

Reference NO 7

http://alanstorm.com/magento_exception_handling_developer_mode

Reference NO 8

http://magento.stackexchange.com/questions/3251/magento-1-8-alpha1-ce-sample-data