PREHOOK: query: DESCRIBE FUNCTION from_unixtime
PREHOOK: type: DESCFUNCTION
POSTHOOK: query: DESCRIBE FUNCTION from_unixtime
POSTHOOK: type: DESCFUNCTION
from_unixtime(unix_time, format) - returns unix_time in the specified format
PREHOOK: query: DESCRIBE FUNCTION EXTENDED from_unixtime
PREHOOK: type: DESCFUNCTION
POSTHOOK: query: DESCRIBE FUNCTION EXTENDED from_unixtime
POSTHOOK: type: DESCFUNCTION
from_unixtime(unix_time, format) - returns unix_time in the specified format
Example:
  > SELECT from_unixtime(0, 'yyyy-MM-dd HH:mm:ss') FROM src LIMIT 1;
  '1970-01-01 00:00:00'