MySQL delete uniqueness constraint unique

First, check the creation table ：

show create table humanidentity.citycode;

drop index citycode_2 on humanidentity.citycode;

drop index citycode_3 on humanidentity.citycode;

I have added here many times unique There are more constraints _2 and _3 了 , Be sure to delete according to the name on this table , Otherwise it won't work . 

 

 

 

Reference documents ：

Remove the uniqueness constraint unique - Run wild ~ - Blog Garden (cnblogs.com)https://www.cnblogs.com/xiangtingshen/p/10982032.html