PREHOOK: query: DESCRIBE FUNCTION datediff
PREHOOK: type: DESCFUNCTION
POSTHOOK: query: DESCRIBE FUNCTION datediff
POSTHOOK: type: DESCFUNCTION
datediff(date1, date2) - Returns the number of days between date1 and date2
PREHOOK: query: DESCRIBE FUNCTION EXTENDED datediff
PREHOOK: type: DESCFUNCTION
POSTHOOK: query: DESCRIBE FUNCTION EXTENDED datediff
POSTHOOK: type: DESCFUNCTION
datediff(date1, date2) - Returns the number of days between date1 and date2
date1 and date2 are strings in the format 'yyyy-MM-dd HH:mm:ss' or 'yyyy-MM-dd'. The time parts are ignored.If date1 is earlier than date2, the result is negative.
Example:
   > SELECT datediff('2009-30-07', '2009-31-07') FROM src LIMIT 1;
  1