mysql mis_exam_question_type 中 学校标识school_id 增加为第二主键

To add "school_id" as a second primary key in the "mis_exam_question_type" table in MySQL, you can use the following SQL query:

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

This query adds a composite primary key consisting of both "question_type_id" and "school_id" columns to the table.