sql 索引操作

1、创建主键索引
alter table table_name add constraint index_name primary key (col1);
2、创建唯一键索引
create unique index uk_name on table_name (col2);
3、创建普通索引
create index index_name on table_name (col3);

例：create index username on sticker_info (username); //sticker_info表加username加索引

4、删除索引
alter table products drop column [ID]