SELECT * FROM class_group_relation WHERE id_ = #{id} SELECT * FROM class_group_relation ORDER BY id_ INSERT INTO class_group_relation (id_,class_group_id_,sub_class_group_id_,create_time_) VALUES(#{id},#{classGroupId},#{subClassGroupId},#{createTime}) UPDATE class_group_relation sub_class_group_id_ = #{subClassGroupId}, class_group_id_ = #{classGroupId}, WHERE id_ = #{id} DELETE FROM class_group_relation WHERE id_ = #{id} SELECT * FROM class_group_relation ORDER BY id_ SELECT COUNT(*) FROM class_group_relation