MySQL replace primary key delete primary key add primary key

Add primary key

alter table humanidentity.citycode add primary key(adcode);

Delete primary key

alter table humanidentity.citycode drop primary key;

Replace primary key

alter table humanidentity.citycode drop primary key;
alter table humanidentity.citycode add primary key(adcode);

Inspection effect

desc humanidentity.citycode;

 

 

Reference documents ：

mysql How to modify Delete add to Table primary key - End of month North - Blog Garden (cnblogs.com)https://www.cnblogs.com/quchengjie/p/10421665.html