- 【TiDB 版本】：v3.0.5
- 【问题描述】：
CREATE TABLE test_wind1 (
id bigint(20) NOT NULL AUTO_INCREMENT,
c2 decimal(20,4) DEFAULT NULL,
c3 smallint(4) DEFAULT NULL ,
PRIMARY KEY (id),
KEY idx_id (id)
);
mysql> alter table test_wind1 drop index idx_id;
ERROR 1075 (42000): Incorrect table definition; there can be only one auto column and it must be defined as a key