PLZ HELP ME

everything has been working well so until a few days there was this website that i was trying to go on but on the of the website page there was this error and i was wondering if someone can help me with this problem.

WordPress database error: [Can’t create/write to file ‘/tmp/#sql_1901_0.MYI’ (Errcode: 28)]
SELECT DISTINCT * FROM wp_posts WHERE 1=1 AND post_date_gmt <= ‘2006-07-06 13:16:59’ AND (post_status = “publish”) AND post_status != “attachment” GROUP BY wp_posts.ID ORDER BY post_date DESC LIMIT 0, 14