hi, good day, i have a question on primary key , currently, i have a table call "newcampaign" which already contain a primary key, named "cam_code", now let say i want to add another primary key"cam_name" to existing "newcampaign" table ,
so i using
alter table newcampaign add PRIMARY KEY (cam_name);");
but it give me error , say multiple primary key defined
so i need to drop all primary key before add both of primary key (cam_name,cam_code)?
another question is , if the table consist of 3 primary key, now i want to drop only one of the primary key , what should i do ? thank you very much !!