Creating an indexed database table requires adding back-quotes to the table name and attributes, and the position of your current primary key needs to be adjusted:

create table `abc`(
   `id` int unsigned auto_increment,
   `usename` char(20) not null default '',
   `gender` char(1) not null default '',
   `weight` tinyint unsigned not null default 0, 
   `birth` date not null default 0,
   `salary` decimal(8,2) not null default '000000.00',
   `lastlogin` timestamp not null default 0,
   `intro` varchar(1500) not null default '',
   primary key (`id`)
)engine myisam charset=utf8;

I just tried it. Except for primary key, other attributes and table names can be used without back-quotes. Even this is also possible:

create table abc(
   id int unsigned auto_increment,
   usename char(20) not null default '',
   gender char(1) not null default '',
   weight tinyint unsigned not null default 0, 
   birth date not null default 0,
   salary decimal(8,2) not null default '000000.00',
   lastlogin timestamp not null default 0,
   intro varchar(1500) not null default '',
   primary key (`id`)
)engine myisam charset=utf8;

Reference: mysql create and delete tables

The declaration of primary_key is wrong, please solve it upstairs