ordPress database error You have an error in your SQL syntax

Got this error in error_log.
[12-Sep-2014 19:05:04 UTC] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 10 for query SELECT DISTINCT ID, post_title, post_password, comment_ID,
comment_post_ID, comment_author, comment_author_email, comment_date_gmt, comment_approved,
SUBSTRING(comment_content,1,80) AS com_excerpt
FROM wp_comments
LEFT OUTER JOIN wp_posts ON (wp_comments.comment_post_ID =
WHERE comment_approved = '1' AND comment_type = '' AND
post_password = ''
ORDER BY comment_date_gmt DESC LIMIT made by require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/blogs-mu/index.php'), locate_template, load_template, require_once('/themes/blogs-mu/index-post.php'), get_sidebar, locate_template, load_template, require_once('/themes/blogs-mu/sidebar.php'), dynamic_sidebar, call_user_func_array, WP_Widget->display_callback, My_WPMUDEV_Recent_Comments_Widget->widget