mysql - SQL Query Primary Key constraint -

i newbie in sql. can please enlighten me on following sql query. problem lies in staffid int not null auto_increment, primary key(personid)

$sql   =   "create   table   persons(staffid   int   not   null  auto_increment, primary  key(personid),firstname  varchar(15),lastname  varchar(15),age  int)"; 

thank you. regards.

you trying create primary key of invalid column, omitting auto increment column. please try below sql. see documentation mysql

create table persons(staffid int auto_increment,       personid varchar(10),      firstname varchar(15),       lastname varchar(15),      age int,       primary key (staffid,personid));