mysql Ìí¼Ó/ɾ³ýÖ÷¼ü

1. mysql±í×Ö¶ÎÌí¼ÓÖ÷¼ü：
2. alter table user add primary key(id);
3. alter table user change id id int(10) not null auto_increment;
5. mysqlɾ³ý±í×Ö¶ÎÖ÷¼ü：
6. alter table user change id id int(10); //ÏÈɾ³ý×ÔÔö³¤
7. alter table user drop primary key; //ÔÙɾ³ýÖ÷¼ü