mysql 错误号1553 MySQL Cannot drop index needed in a foreign key constraint,外键也会创建索引
表被参照表:|teacher|CREATETABLE`teacher`(`id`varchar(20)NOTNULL,`name`varchar(255)DEFAULTNULL,`salary`decimal(10,2)DEFAULTNULL,PRIMARYKEY(`id`))ENGINE=InnoDBDEFAULTCHARSET=utf8|参照表:|teacher_student|CREATET