mysql创建修改删除索引

alter table table_name add unique index(column_name,column_name);
示例如下:
ALTER TABLE `yzj_need_member` ADD UNIQUE (`user_id`, `need_id`);

alter table table_name add unique index(column_name,column_name); 示例如下: ALTER TABLE `yzj_need_member` ADD UNIQUE (`user_id`, `need_id`);