id, teaching_class_id, student_user_id, admin_class_id, status, join_reason, join_time, exit_time, create_time select count(*) from teaching_class_student where teaching_class_id = #{teachingClassId,jdbcType=VARCHAR} select count(*) from teaching_class_student where student_user_id = #{studentUserId,jdbcType=VARCHAR} and teaching_class_id = #{teachingClassId,jdbcType=VARCHAR} select from teaching_class_student where teaching_class_id = #{teachingClassId,jdbcType=VARCHAR} insert into teaching_class_student id, teaching_class_id, student_user_id, admin_class_id, status, join_reason, join_time, exit_time, create_time, #{id,jdbcType=VARCHAR}, #{teachingClassId,jdbcType=VARCHAR}, #{studentUserId,jdbcType=VARCHAR}, #{adminClassId,jdbcType=VARCHAR}, #{status,jdbcType=VARCHAR}, #{joinReason,jdbcType=VARCHAR}, #{joinTime,jdbcType=TIMESTAMP}, #{exitTime,jdbcType=TIMESTAMP}, #{createTime,jdbcType=TIMESTAMP}, delete from teaching_class_student where teaching_class_id = #{teachingClassId,jdbcType=VARCHAR}