select timestampdiff(microsecond,'2000-01-01 00:00:00','2001-01-01 00:00:00.123456') as exp;
exp
31622400123456
explain extended select timestampdiff(microsecond,'2000-01-01 00:00:00','2001-01-01 00:00:00.123456') as exp;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1003	select timestampdiff(MICROSECOND,'2000-01-01 00:00:00','2001-01-01 00:00:00.123456') AS `exp`
create view v1 as select timestampdiff(microsecond,'2000-01-01 00:00:00','2001-01-01 00:00:00.123456') as exp;
select * from v1;
exp
31622400123456
drop view v1;