CREATE TABLE t1 (
`i1` INT(10) UNSIGNED NOT NULL,
`d1` TIMESTAMP NULL DEFAULT NULL
) ENGINE=innodb;
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `i1` int(10) unsigned NOT NULL,
  `d1` timestamp NULL DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
INSERT INTO t1 (i1) VALUES (1), (2), (3), (4), (5);
select * from t1;
i1	d1
1	NULL
2	NULL
3	NULL
4	NULL
5	NULL
set sql_mode = 'STRICT_ALL_TABLES,NO_ZERO_DATE';
ALTER TABLE t1 CHANGE `d1` `d1` TIMESTAMP DEFAULT CURRENT_TIMESTAMP  NOT NULL;
drop table t1;
CREATE TABLE t1 (
`i1` INT(10) UNSIGNED NOT NULL,
`d1` TIMESTAMP NULL DEFAULT NULL
) ENGINE=innodb;
INSERT INTO t1 (i1) VALUES (1), (2), (3), (4), (5);
ALTER TABLE t1 CHANGE `d1` `d1` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP;
drop table t1;
set sql_mode = '';