case1:
ALTER TABLE `mydb`.`cd00_feihu` CHANGE `t1` `t1` TIMESTAMP DEFAULT NULL NULL;ALTER TABLE `mydb`.`cd00_feihu` CHANGE `t1`
case1:
ALTER TABLE `mydb`.`cd00_feihu` CHANGE `t1` `t1` TIMESTAMP DEFAULT NULL NULL;ALTER TABLE `mydb`.`cd00_feihu` CHANGE `t1`