there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause

create table `product_category` (

    `category_id` int not null auto_increment,

    `category_name` varchar(64) not null comment '类目名字',

    `category_type` int not null comment '类目编号',

    `create_time` timestamp not null default current_timestamp comment '创建时间',

    `update_time` timestamp not null  default current_timestamp on update current_timestamp  comment '修改时间',

    primary key (`category_id`),

    unique key `uqe_category_type` (`category_type`)

);

create table `product_category` (

    `category_id` int not null auto_increment,

    `category_name` varchar(64) not null comment '类目名字',

    `category_type` int not null comment '类目编号',

    `create_time` timestamp not null comment '创建时间',

    `update_time` timestamp not null  DEFAULT current_timestamp  comment '修改时间',

    primary key (`category_id`),

    unique key `uqe_category_type` (`category_type`)

);

上面sql在5.5版本会报如下错误:

Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause

在5.7版本不会报错