MySQL returned error

Error Description :

Error No : 1021
Description : Disk full (/tmp/#sql_266_0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")

SQL Query
SELECT `project`.* FROM `project` WHERE id!=0 AND project.status='Active' and set_as_home_detail='Yes' ORDER BY rand() limit 0,1