mysql mis_exam_course_id_switch中删除唯一性索引 sys_course_id_2；mis_exam_type中删除唯一性索引 sys_exam_type_id；mis_exam_question_type 中 学校标识school_id 设置为主键

To delete the unique index sys_course_id_2 from the table mis_exam_course_id_switch in MySQL, you can use the following command:

ALTER TABLE mis_exam_course_id_switch DROP INDEX sys_course_id_2;

To delete the unique index sys_exam_type_id from the table mis_exam_type, you can use the following command:

ALTER TABLE mis_exam_type DROP INDEX sys_exam_type_id;

To set the column school_id as the primary key in the table mis_exam_question_type and remove any existing primary key, you can use the following command:

ALTER TABLE mis_exam_question_type DROP PRIMARY KEY, ADD PRIMARY KEY (school_id);

Make sure to replace the table and index names with the correct ones in your database. Also, be cautious when modifying the structure of the tables as it can affect the data integrity and functionality of your application